What's new in Java 19: The end of Kotlin? (KotlinConf 2019)

Kotlin's introduction was a breath of fresh air at a time when the pace of innovation in Java felt glacial. Since that time, development of Java has rapidly increased with an emphasis on fixing the pain points of the language and the efficiency of data representation in the VM. Will Kotlin still have a place in the JVM language ecosystem in a few years?

This talk will compare and contrast how the two languages approach solving the same problems of today's Java. We'll look at data-carrying types, asynchronous programming, nullability, and more. For some of these, we'll also see how one language sometimes influenced the other. Finally, we'll peer a few years into the future to see where both languages are headed and determine whether we still need a Kotlin (spoiler: we probably do!).

Video: https://youtu.be/te3OU9fxC8U

Transcript

1. What's new in Java 19:
   The end of Kotlin?
   @JakeWharton
   

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2. January 23, 1996
   Java 1
   

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3. September 30, 2004
   Java 5
   

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4. July 28, 2011
   Java 7
   

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5. March 18, 2014
   Java 8
   

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6. September 21, 2017
   Java 9
   

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7. September 21, 2017
   Java 9
   March 20, 2018
   Java 10
   

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8. March 20, 2018
   Java 10
   September 25, 2018
   Java 11
   

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9. September 25, 2018
   Java 11
   March 19, 2019
   Java 12
   

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10. March 19, 2019
    Java 12
    September 17, 2019
    Java 13
    

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11. March 2020
    Java 14
    September 2020
    Java 15
    

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12. March 2021
    Java 16
    September 2021
    Java 17
    

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13. March 2022
    Java 18
    September 2022
    Java 19
    

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14. 8
    September 2022
    Java 19
    

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15. 8
    September 2022
    Java 19 YOU
    ARE
    HERE
    

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16. Variable Type Inference
    

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17. var count = 1
    

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18. var count = 1
    var count = 1
    

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19. var count = 1
    val users = mutableListOf()
    var count = 1
    

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20. var count = 1
    val users = mutableListOf()
    var count = 1
    final var users = new ArrayList()
    

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21. var count = 1
    val users = mutableListOf()
    var default: String? = null
    var count = 1
    final var users = new ArrayList()
    

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22. var count = 1
    val users = mutableListOf()
    var default: String? = null
    var count = 1
    final var users = new ArrayList()
    String default = null
    

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23. var count = 1
    val users = mutableListOf()
    var default: String? = null
    val tasks: Deque = ArrayDeque()
    var count = 1
    final var users = new ArrayList()
    String default = null
    

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24. var count = 1
    val users = mutableListOf()
    var default: String? = null
    val tasks: Deque = ArrayDeque()
    var count = 1
    final var users = new ArrayList()
    String default = null
    Deque tasks = new ArrayDeque<>()
    

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25. val run1: () -> Unit = { /* .. */ }
    

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26. val run1: () -> Unit = { /* .. */ }
    val run2 = { /* .. */ }
    

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27. val run1: () -> Unit = { /* .. */ }
    val run2 = { /* .. */ }
    Runnable run1 = () -> { /* .. */ };
    

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28. val run1: () -> Unit = { /* .. */ }
    val run2 = { /* .. */ }
    Runnable run1 = () -> { /* .. */ };
    var run2 = () -> { /* .. */ };
    

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29. val run1: () -> Unit = { /* .. */ }
    val run2 = { /* .. */ }
    Runnable run1 = () -> { /* .. */ };
    var run2 = new Runnable() {
    @Override public void run() {
    /* .. */
    }
    };
    

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30. var count = 1
    val users = mutableListOf()
    var default: String? = null
    val tasks: Deque = ArrayDeque()
    val run1: () -> Unit = { /* .. */ }
    val run2 = { /* .. */ }
    var count = 1
    final var users = new ArrayList()
    String default = null
    Deque tasks = new ArrayDeque<>()
    Runnable run1 = () -> { /* .. */ };
    var run2 = new Runnable() {
    @Override public void run() { /* .. */ }
    };
    

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31. Local Functions
    

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32. fun Graph.any(predicate: (Node) -> Boolean): Boolean {
    val seen = HashSet()
    fun Node.hasMatch(): Boolean {
    if (!seen.add(this)) return false // already seen
    if (predicate(this)) return true // match!
    return nodes.any { it.hasMatch() }
    }
    return root.hasMatch()
    }
    

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33. fun Graph.any(predicate: (Node) -> Boolean): Boolean {
    val seen = HashSet()
    fun Node.hasMatch(): Boolean {
    if (!seen.add(this)) return false // already seen
    if (predicate(this)) return true // match!
    return nodes.any { it.hasMatch() }
    }
    return root.hasMatch()
    }
    

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34. fun Graph.any(predicate: (Node) -> Boolean): Boolean {
    val seen = HashSet()
    fun Node.hasMatch(): Boolean {
    if (!seen.add(this)) return false // already seen
    if (predicate(this)) return true // match!
    return nodes.any { it.hasMatch() }
    }
    return root.hasMatch()
    }
    

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35. fun Graph.any(predicate: (Node) -> Boolean): Boolean {
    val seen = HashSet()
    fun Node.hasMatch(): Boolean {
    if (!seen.add(this)) return false // already seen
    if (predicate(this)) return true // match!
    return nodes.any { it.hasMatch() }
    }
    return root.hasMatch()
    }
    

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36. fun Graph.any(predicate: (Node) -> Boolean): Boolean {
    val seen = HashSet()
    fun Node.hasMatch(): Boolean {
    if (!seen.add(this)) return false // already seen
    if (predicate(this)) return true // match!
    return nodes.any { it.hasMatch() }
    }
    return root.hasMatch()
    }
    

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37. fun Graph.any(predicate: (Node) -> Boolean): Boolean {
    val seen = HashSet()
    fun Node.hasMatch(): Boolean {
    if (!seen.add(this)) return false // already seen
    if (predicate(this)) return true // match!
    return nodes.any { it.hasMatch() }
    }
    return root.hasMatch()
    }
    public static boolean any(Predicate predicate) {
    var seen = new HashSet();
    boolean hasMatch(Node node) {
    if (!seen.add(node)) return false; // already seen
    if (predicate.test(node)) return true; // match!
    return node.getNodes().stream().anyMatch(n -> hasMatch(n));
    }
    return hasMatch(getRoot());
    }
    

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38. public static boolean any(Predicate predicate) {
    var seen = new HashSet();
    boolean hasMatch(Node node) {
    if (!seen.add(node)) return false; // already seen
    if (predicate.test(node)) return true; // match!
    return node.getNodes().stream().anyMatch(n -> hasMatch(n));
    }
    return hasMatch(getRoot());
    }
    

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39. public static boolean any(
    Graph, java.util.function.Predicate);
    Code:
    0: new #7 // class java/util/HashSet
    3: dup
    4: invokespecial #9 // Method java/util/HashSet."":()V
    7: astore_2
    8: aload_2
    9: aload_1
    10: aload_0
    11: invokevirtual #10 // Method getRoot:()Lcom/example/Node;
    14: invokestatic #16 // Method local$any$0(...)Z
    17: ireturn
    private static boolean local$any$0(
    java.util.HashSet, java.util.function.Predicate, Node);
    Code:
    ...
    

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40. public static boolean any(
    Graph, java.util.function.Predicate);
    Code:
    0: new #7 // class java/util/HashSet
    3: dup
    4: invokespecial #9 // Method java/util/HashSet."":()V
    7: astore_2
    8: aload_2
    9: aload_1
    10: aload_0
    11: invokevirtual #10 // Method getRoot:()Lcom/example/Node;
    14: invokestatic #16 // Method local$any$0(...)Z
    17: ireturn
    private static boolean local$any$0(
    java.util.HashSet, java.util.function.Predicate, Node);
    Code:
    ...
    

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41. public static boolean any(
    Graph, java.util.function.Predicate);
    Code:
    0: new #7 // class java/util/HashSet
    3: dup
    4: invokespecial #9 // Method java/util/HashSet."":()V
    7: astore_2
    8: aload_2
    9: aload_1
    10: aload_0
    11: invokevirtual #10 // Method getRoot:()Lcom/example/Node;
    14: invokestatic #16 // Method local$any$0(...)Z
    17: ireturn
    private static boolean local$any$0(
    java.util.HashSet, java.util.function.Predicate, Node);
    Code:
    ...
    

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42. public static boolean any(Predicate predicate) {
    var seen = new HashSet();
    boolean hasMatch(Node node) {
    if (!seen.add(node)) return false; // already seen
    if (predicate.test(node)) return true; // match!
    return node.getNodes().stream().anyMatch(n -> hasMatch(n));
    }
    return hasMatch(getRoot());
    }
    

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43. fun Graph.any(predicate: (Node) -> Boolean): Boolean {
    val seen = HashSet()
    fun Node.hasMatch(): Boolean {
    if (!seen.add(this)) return false // already seen
    if (predicate(this)) return true // match!
    return nodes.any { it.hasMatch() }
    }
    return root.hasMatch()
    }
    

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44. public static boolean any(
    Graph, kotlin.jvm.functions.Function1);
    Code:
    0: new #20 // class java/util/HashSet
    3: dup
    4: invokespecial #24 // Method java/util/HashSet."":()V
    7: astore_2
    8: new #26 // class GraphKt$any$1
    11: dup
    12: aload_2
    13: aload_1
    14: invokespecial #29 // Method GraphKt$any$1."":
    (Ljava/util/HashSet;
    Lkotlin/jvm/functions/Function1;)V
    17: astore_3
    18: aload_3
    19: aload_0
    20: invokeinterface #35, 1 // InterfaceMethod Graph.getRoot:()LNode;
    25: invokevirtual #39 // Method GraphKt$any$1.invoke:(LNode;)Z
    28: ireturn
    

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45. public static boolean any(
    Graph, kotlin.jvm.functions.Function1);
    Code:
    0: new #20 // class java/util/HashSet
    3: dup
    4: invokespecial #24 // Method java/util/HashSet."":()V
    7: astore_2
    8: new #26 // class GraphKt$any$1
    11: dup
    12: aload_2
    13: aload_1
    14: invokespecial #29 // Method GraphKt$any$1."":
    (Ljava/util/HashSet;
    Lkotlin/jvm/functions/Function1;)V
    17: astore_3
    18: aload_3
    19: aload_0
    20: invokeinterface #35, 1 // InterfaceMethod Graph.getRoot:()LNode;
    25: invokevirtual #39 // Method GraphKt$any$1.invoke:(LNode;)Z
    28: ireturn
    

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46. public static boolean any(
    Graph, kotlin.jvm.functions.Function1);
    Code:
    0: new #20 // class java/util/HashSet
    3: dup
    4: invokespecial #24 // Method java/util/HashSet."":()V
    7: astore_2
    8: new #26 // class GraphKt$any$1
    11: dup
    12: aload_2
    13: aload_1
    14: invokespecial #29 // Method GraphKt$any$1."":
    (Ljava/util/HashSet;
    Lkotlin/jvm/functions/Function1;)V
    17: astore_3
    18: aload_3
    19: aload_0
    20: invokeinterface #35, 1 // InterfaceMethod Graph.getRoot:()LNode;
    25: invokevirtual #39 // Method GraphKt$any$1.invoke:(LNode;)Z
    28: ireturn
    

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47. public static boolean any(
    Graph, kotlin.jvm.functions.Function1);
    Code:
    0: new #20 // class java/util/HashSet
    3: dup
    4: invokespecial #24 // Method java/util/HashSet."":()V
    7: astore_2
    8: new #26 // class GraphKt$any$1
    11: dup
    12: aload_2
    13: aload_1
    14: invokespecial #29 // Method GraphKt$any$1."":
    (Ljava/util/HashSet;
    Lkotlin/jvm/functions/Function1;)V
    17: astore_3
    18: aload_3
    19: aload_0
    20: invokeinterface #35, 1 // InterfaceMethod Graph.getRoot:()LNode;
    25: invokevirtual #39 // Method GraphKt$any$1.invoke:(LNode;)Z
    28: ireturn
    

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48. final class GraphKt$any$1
    extends kotlin.jvm.internal.Lambda
    implements kotlin.jvm.functions.Function1 {
    final java.util.HashSet $seen;
    final kotlin.jvm.functions.Function1 $predicate;
    GraphKt$any$1(java.util.HashSet, kotlin.jvm.functions.Function1);
    Code:
    ...
    public final boolean invoke(Node);
    Code:
    ...
    }
    

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49. final class GraphKt$any$1
    extends kotlin.jvm.internal.Lambda
    implements kotlin.jvm.functions.Function1 {
    final java.util.HashSet $seen;
    final kotlin.jvm.functions.Function1 $predicate;
    GraphKt$any$1(java.util.HashSet, kotlin.jvm.functions.Function1);
    Code:
    ...
    public final boolean invoke(Node);
    Code:
    ...
    }
    

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50. final class GraphKt$any$1
    extends kotlin.jvm.internal.Lambda
    implements kotlin.jvm.functions.Function1 {
    final java.util.HashSet $seen;
    final kotlin.jvm.functions.Function1 $predicate;
    GraphKt$any$1(java.util.HashSet, kotlin.jvm.functions.Function1);
    Code:
    ...
    public final boolean invoke(Node);
    Code:
    ...
    }
    

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51. final class GraphKt$any$1
    extends kotlin.jvm.internal.Lambda
    implements kotlin.jvm.functions.Function1 {
    final java.util.HashSet $seen;
    final kotlin.jvm.functions.Function1 $predicate;
    GraphKt$any$1(java.util.HashSet, kotlin.jvm.functions.Function1);
    Code:
    ...
    public final boolean invoke(Node);
    Code:
    ...
    }
    

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52. final class GraphKt$any$1
    extends kotlin.jvm.internal.Lambda
    implements kotlin.jvm.functions.Function1 {
    final java.util.HashSet $seen;
    final kotlin.jvm.functions.Function1 $predicate;
    GraphKt$any$1(java.util.HashSet, kotlin.jvm.functions.Function1);
    Code:
    ...
    public final boolean invoke(Node);
    Code:
    ...
    }
    

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53. fun Graph.any(predicate: (Node) -> Boolean): Boolean {
    val seen = HashSet()
    fun Node.hasMatch(): Boolean {
    if (!seen.add(this)) return false // already seen
    if (predicate(this)) return true // match!
    return nodes.any { it.hasMatch() }
    }
    return root.hasMatch()
    }
    

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54. fun Graph.any(predicate: (Node) -> Boolean): Boolean {
    val seen = HashSet()
    fun Node.hasMatch(): Boolean {
    if (!seen.add(this)) return false // already seen
    if (predicate(this)) return true // match!
    return nodes.any { it.hasMatch() }
    }
    return root.hasMatch()
    }
    "Optimize generation of local functions"
    youtrack.jetbrains.com/issue/KT-6336
    

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55. fun Graph.any(predicate: (Node) -> Boolean): Boolean {
    val seen = HashSet()
    fun Node.hasMatch(): Boolean {
    if (!seen.add(this)) return false // already seen
    if (predicate(this)) return true // match!
    return nodes.any { it.hasMatch() }
    }
    return root.hasMatch()
    }
    "Consider more aggresively removing classes from Kotlin local functions"
    issuetracker.google.com/issues/145231155
    

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56. fun Graph.any(predicate: (Node) -> Boolean): Boolean {
    val seen = HashSet()
    fun Node.hasMatch(): Boolean {
    if (!seen.add(this)) return false // already seen
    if (predicate(this)) return true // match!
    return nodes.any { it.hasMatch() }
    }
    return root.hasMatch()
    }
    public static boolean any(Predicate predicate) {
    var seen = new HashSet();
    boolean hasMatch(Node node) {
    if (!seen.add(node)) return false; // already seen
    if (predicate.test(node)) return true; // match!
    return node.getNodes().stream().anyMatch(n -> hasMatch(n));
    }
    return hasMatch(getRoot());
    }
    

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57. Multiline Strings
    

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58. fun main() {
    println("""
    SELECT *
    FROM users
    WHERE name LIKE 'Jake %'
    """)
    }
    

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59. fun main() {
    println("""
    SELECT *
    FROM users
    WHERE name LIKE 'Jake %'
    """)
    }
    ····SELECT *
    ····FROM users
    ····WHERE name LIKE 'Jake %'
    ··
    

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60. fun main() {
    println("""
    |SELECT *
    |FROM users
    |WHERE name LIKE 'Jake %'
    |""".trimMargin())
    }
    SELECT *
    FROM users
    WHERE name LIKE 'Jake %'
    

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61. fun main() {
    println("""
    !!!SELECT *
    !!!FROM users
    !!!WHERE name LIKE 'Jake %'
    !!!""".trimMargin(marginPrefix = "!!!"))
    }
    SELECT *
    FROM users
    WHERE name LIKE 'Jake %'
    

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62. fun main() {
    println("""
    SELECT *
    FROM users
    WHERE name LIKE 'Jake %'
    """.trimIndent())
    }
    SELECT *
    FROM users
    WHERE name LIKE 'Jake %'
    Margin m
    a
    r
    g
    i
    n
    P
    r
    e
    f
    i
    x = "
    !
    !
    !
    "
    

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63. fun main() {
    println("""
    SELECT *
    FROM users
    WHERE name LIKE 'Jake %'
    """.trimIndent())
    }
    public static void main(String[] args) {
    System.out.println("""
    SELECT *
    FROM users
    WHERE name LIKE 'Jake %'
    """);
    }
    

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64. public static void main(String[] args) {
    System.out.println("""
    SELECT *
    FROM users
    WHERE name LIKE 'Jake %'
    """);
    }
    

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65. public static void main(String[] args) {
    System.out.println("""
    SELECT *
    FROM users
    WHERE name LIKE 'Jake %'
    """);
    }
    SELECT *
    FROM users
    WHERE name LIKE 'Jake %'
    

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66. public static void main(String[] args) {
    System.out.println("""
    SELECT *
    FROM users
    WHERE name LIKE 'Jake %'
    """);
    }
    SELECT *
    FROM users
    WHERE name LIKE 'Jake %'
    

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67. public static void main(String[] args) {
    System.out.println("""
    SELECT * \
    FROM users \
    WHERE name LIKE 'Jake %'
    """);
    }
    SELECT * FROM users WHERE name LIKE 'Jake %'
    

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68. assertThat(table.toString()).isEqualTo("""
    |┌─┬─┐ ╷
    |│ │ │ │
    |├─┤ ╵ │
    |│ │ │
    |└─┼───┘
    | │
    |╶─┴─╴
    |""".trimMargin())
    

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69. assertThat(table.toString()).isEqualTo("""
    ··|┌─┬─┐·╷
    ··|│·│·│·│
    ··|├─┤·╵·│
    ··|│·│···│
    ··|└─┼───┘
    ··|··│····
    ··|╶─┴─╴··
    ··|""".trimMargin())
    

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70. assertThat(table.toString()).isEqualTo("""
    ··|┌─┬─┐·╷
    ··|│·│·│·│
    ··|├─┤·╵·│
    ··|│·│···│
    ··|└─┼───┘
    ··|··│····
    ··|╶─┴─╴··
    ··|""".trimMargin())
    assertThat(table.toString()).isEqualTo("""
    ····┌─┬─┐·╷
    ····│·│·│·│
    ····├─┤·╵·│
    ····│·│···│
    ····└─┼───┘
    ······│····
    ····╶─┴─╴··
    ····""");
    

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71. assertThat(table.toString()).isEqualTo("""
    ··|┌─┬─┐·╷
    ··|│·│·│·│
    ··|├─┤·╵·│
    ··|│·│···│
    ··|└─┼───┘
    ··|··│····
    ··|╶─┴─╴··
    ··|""".trimMargin())
    assertThat(table.toString()).isEqualTo("""
    ····┌─┬─┐·╷
    ····│·│·│·│
    ····├─┤·╵·│
    ····│·│···│
    ····└─┼───┘
    ······│····
    ····╶─┴─╴··
    ····""");
    

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72. assertThat(table.toString()).isEqualTo("""
    ··|┌─┬─┐·╷
    ··|│·│·│·│
    ··|├─┤·╵·│
    ··|│·│···│
    ··|└─┼───┘
    ··|··│····
    ··|╶─┴─╴··
    ··|""".trimMargin())
    assertThat(table.toString()).isEqualTo("""
    ····┌─┬─┐·╷
    ····│·│·│·│
    ····├─┤·╵·│
    ····│·│···│
    ····└─┼───┘
    ······│···\s
    ····╶─┴─╴·\s
    ····""");
    

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73. println("""
    Hey $name!
    Hola $name!
    Hello $name!
    """.trimIndent())
    

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74. public static final void sayHi(java.lang.String);
    Code:
    0: new #17 // class java/lang/StringBuilder
    3: dup
    4: invokespecial #21 // Method java/lang/StringBuilder."":()V
    7: ldc #23 // String \n Hey
    9: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    12: aload_0
    13: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    16: ldc #29 // String !\n Hola
    18: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    21: aload_0
    22: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    25: ldc #31 // String !\n Hello
    27: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    30: aload_0
    31: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    34: ldc #33 // String !\n
    36: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    39: invokevirtual #37 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
    42: invokestatic #43 // Method kotlin/text/StringsKt.trimIndent:(Ljava/lang/String;)…;
    45: astore_1
    46: getstatic #49 // Field java/lang/System.out:Ljava/io/PrintStream;
    49: aload_1
    50: invokevirtual #55 // Method java/io/PrintStream.println:(Ljava/lang/Object;)V
    53: return
    

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75. public static final void sayHi(java.lang.String);
    Code:
    0: new #17 // class java/lang/StringBuilder
    3: dup
    4: invokespecial #21 // Method java/lang/StringBuilder."":()V
    7: ldc #23 // String \n Hey
    9: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    12: aload_0
    13: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    16: ldc #29 // String !\n Hola
    18: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    21: aload_0
    22: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    25: ldc #31 // String !\n Hello
    27: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    30: aload_0
    31: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    34: ldc #33 // String !\n
    36: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    39: invokevirtual #37 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
    42: invokestatic #43 // Method kotlin/text/StringsKt.trimIndent:(Ljava/lang/String;)…;
    45: astore_1
    46: getstatic #49 // Field java/lang/System.out:Ljava/io/PrintStream;
    49: aload_1
    50: invokevirtual #55 // Method java/io/PrintStream.println:(Ljava/lang/Object;)V
    53: return
    

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76. public static final void sayHi(java.lang.String);
    Code:
    0: new #17 // class java/lang/StringBuilder
    3: dup
    4: invokespecial #21 // Method java/lang/StringBuilder."":()V
    7: ldc #23 // String \n Hey
    9: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    12: aload_0
    13: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    16: ldc #29 // String !\n Hola
    18: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    21: aload_0
    22: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    25: ldc #31 // String !\n Hello
    27: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    30: aload_0
    31: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    34: ldc #33 // String !\n
    36: invokevirtual #27 // Method java/lang/StringBuilder.append:(…)…;
    39: invokevirtual #37 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
    42: invokestatic #43 // Method kotlin/text/StringsKt.trimIndent:(Ljava/lang/String;)…;
    45: astore_1
    46: getstatic #49 // Field java/lang/System.out:Ljava/io/PrintStream;
    49: aload_1
    50: invokevirtual #55 // Method java/io/PrintStream.println:(Ljava/lang/Object;)V
    53: return
    

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77. println("""
    Hey $name!
    Hola $name!
    Hello $name!
    """.trimIndent())
    

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78. println("""
    Hey $name!
    Hola $name!
    Hello $name!
    """.trimIndent())
    System.out.println(""
    + "Hey " + name + "!\n"
    + " Hola " + name + "!\n"
    + " Hello " + name + "!");
    

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79. System.out.println(""
    + "Hey " + name + "!\n"
    + " Hola " + name + "!\n"
    + " Hello " + name + "!");
    

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80. public static void sayHi(java.lang.String);
    Code:
    0: getstatic #2 // Field java/lang/System.out:…
    3: aload_0
    4: aload_0
    5: aload_0
    6: invokedynamic #3, 0 // InvokeDynamic #0:makeConcatWithConstants:
    (Ljava/lang/String;
    Ljava/lang/String;
    Ljava/lang/String;)Ljava/lang/String;
    11: invokevirtual #4 // Method java/io/PrintStream.println:(…)V
    14: return
    

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81. public static void sayHi(java.lang.String);
    Code:
    0: getstatic #2 // Field java/lang/System.out:…
    3: aload_0
    4: aload_0
    5: aload_0
    6: invokedynamic #3, 0 // InvokeDynamic #0:makeConcatWithConstants:
    (Ljava/lang/String;
    Ljava/lang/String;
    Ljava/lang/String;)Ljava/lang/String;
    11: invokevirtual #4 // Method java/io/PrintStream.println:(…)V
    14: return
    

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82. public static void sayHi(java.lang.String);
    Code:
    0: getstatic #2 // Field java/lang/System.out:…
    3: aload_0
    4: aload_0
    5: aload_0
    6: invokedynamic #3, 0 // InvokeDynamic #0:makeConcatWithConstants:
    (Ljava/lang/String;
    Ljava/lang/String;
    Ljava/lang/String;)Ljava/lang/String;
    11: invokevirtual #4 // Method java/io/PrintStream.println:(…)V
    14: return
    BootstrapMethods:
    0: #19 REF_invokeStatic
    java/lang/invoke/StringConcatFactory.makeConcatWithConstants:
    (Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;
    Ljava/lang/invoke/MethodType;Ljava/lang/String;
    [Ljava/lang/Object;)Ljava/lang/invoke/CallSite;
    Method arguments:
    #20 Hey \u0001!\n Hola \u0001!\n Hello \u0001!
    

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83. public static void sayHi(java.lang.String);
    Code:
    0: getstatic #2 // Field java/lang/System.out:…
    3: aload_0
    4: aload_0
    5: aload_0
    6: invokedynamic #3, 0 // InvokeDynamic #0:makeConcatWithConstants:
    (Ljava/lang/String;
    Ljava/lang/String;
    Ljava/lang/String;)Ljava/lang/String;
    11: invokevirtual #4 // Method java/io/PrintStream.println:(…)V
    14: return
    BootstrapMethods:
    0: #19 REF_invokeStatic
    java/lang/invoke/StringConcatFactory.makeConcatWithConstants:
    (Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;
    Ljava/lang/invoke/MethodType;Ljava/lang/String;
    [Ljava/lang/Object;)Ljava/lang/invoke/CallSite;
    Method arguments:
    #20 Hey \u0001!\n Hola \u0001!\n Hello \u0001!
    

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84. System.out.println(""
    + "Hey " + name + "!\n"
    + " Hola " + name + "!\n"
    + " Hello " + name + "!");
    

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85. System.out.println("""
    Hey %s!
    Hola %s!
    Hello %s!
    """.formatted(name, name, name));
    

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86. public static void sayHi(java.lang.String);
    Code:
    0: getstatic #9 // Field java/lang/System.out:…
    3: aload_0
    4: aload_0
    5: aload_0
    6: invokedynamic #15, 0 // InvokeDynamic #0:format:
    (Ljava/lang/String;
    Ljava/lang/String;
    Ljava/lang/String;)Ljava/lang/String;
    11: invokevirtual #19 // Method java/io/PrintStream.println:(…)V
    14: return
    

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87. public static void sayHi(java.lang.String);
    Code:
    0: getstatic #9 // Field java/lang/System.out:…
    3: aload_0
    4: aload_0
    5: aload_0
    6: invokedynamic #15, 0 // InvokeDynamic #0:format:
    (Ljava/lang/String;
    Ljava/lang/String;
    Ljava/lang/String;)Ljava/lang/String;
    11: invokevirtual #19 // Method java/io/PrintStream.println:(…)V
    14: return
    

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88. public static void sayHi(java.lang.String);
    Code:
    0: getstatic #9 // Field java/lang/System.out:…
    3: aload_0
    4: aload_0
    5: aload_0
    6: invokedynamic #15, 0 // InvokeDynamic #0:format:
    (Ljava/lang/String;
    Ljava/lang/String;
    Ljava/lang/String;)Ljava/lang/String;
    11: invokevirtual #19 // Method java/io/PrintStream.println:(…)V
    14: return
    BootstrapMethods:
    0: #34 REF_invokeStatic java/util/Formatter.formatterBootstrap:
    (Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;
    Ljava/lang/invoke/MethodType;Ljava/lang/String;II)…
    Method arguments:
    #41 Hey %s!\n Hola %s!\n Hello %s!
    #43 1
    #44 0
    

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89. public static void sayHi(java.lang.String);
    Code:
    0: getstatic #9 // Field java/lang/System.out:…
    3: aload_0
    4: aload_0
    5: aload_0
    6: invokedynamic #15, 0 // InvokeDynamic #0:format:
    (Ljava/lang/String;
    Ljava/lang/String;
    Ljava/lang/String;)Ljava/lang/String;
    11: invokevirtual #19 // Method java/io/PrintStream.println:(…)V
    14: return
    BootstrapMethods:
    0: #34 REF_invokeStatic java/util/Formatter.formatterBootstrap:
    (Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;
    Ljava/lang/invoke/MethodType;Ljava/lang/String;II)…
    Method arguments:
    #41 Hey %s!\n Hola %s!\n Hello %s!
    #43 1
    #44 0
    

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90. System.out.println("""
    Hey %s!
    Hola %s!
    Hello %s!
    """.formatted(name, name, name));
    

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91. println("""
    Hey $name!
    Hola $name!
    Hello $name!
    """.trimIndent())
    System.out.println("""
    Hey %s!
    Hola %s!
    Hello %s!
    """.formatted(name, name, name));
    

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92. println("""
    Hey $name!
    Hola $name!
    Hello $name!
    """.trimIndent())
    System.out.println("""
    Hey %s!
    Hola %s!
    Hello %s!
    """.formatted(name, name, name));
    "Indify String Concatenation (StringConcatFactory)"
    youtrack.jetbrains.com/issue/KT-21147
    

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93. Value-Based Classes
    

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94. data class Person(val name: String, val age: Int)
    

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95. data class Person(val name: String, val age: Int)
    record Person(String name, int age) { }
    

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96. public final class Person {
    private final java.lang.String name;
    private final int age;
    public Person(java.lang.String, int);
    public java.lang.String getName();
    public int getAge();
    public java.lang.String toString();
    public int hashCode();
    public boolean equals(java.lang.Object);
    // copy and component methods omitted…
    }
    public final class Person extends java.lang.Record {
    private final java.lang.String name;
    private final int age;
    public Person(java.lang.String, int);
    public java.lang.String name();
    public int age();
    public java.lang.String toString();
    public int hashCode();
    public boolean equals(java.lang.Object);
    }
    

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97. public final class Person {
    private final java.lang.String name;
    private final int age;
    public Person(java.lang.String, int);
    public java.lang.String getName();
    public int getAge();
    public java.lang.String toString();
    public int hashCode();
    public boolean equals(java.lang.Object);
    // copy and component methods omitted…
    }
    public final class Person extends java.lang.Record {
    private final java.lang.String name;
    private final int age;
    public Person(java.lang.String, int);
    public java.lang.String name();
    public int age();
    public java.lang.String toString();
    public int hashCode();
    public boolean equals(java.lang.Object);
    }
    

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98. public final class Person {
    private final java.lang.String name;
    private final int age;
    public Person(java.lang.String, int);
    public java.lang.String getName();
    public int getAge();
    public java.lang.String toString();
    public int hashCode();
    public boolean equals(java.lang.Object);
    // copy and component methods omitted…
    }
    public final class Person extends java.lang.Record {
    private final java.lang.String name;
    private final int age;
    public Person(java.lang.String, int);
    public java.lang.String name();
    public int age();
    public java.lang.String toString();
    public int hashCode();
    public boolean equals(java.lang.Object);
    }
    

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99. public final class Person {
    private final java.lang.String name;
    private final int age;
    public Person(java.lang.String, int);
    public java.lang.String getName();
    public int getAge();
    public java.lang.String toString();
    public int hashCode();
    public boolean equals(java.lang.Object);
    // copy and component methods omitted…
    }
    public final class Person extends java.lang.Record {
    private final java.lang.String name;
    private final int age;
    public Person(java.lang.String, int);
    public java.lang.String name();
    public int age();
    public java.lang.String toString();
    public int hashCode();
    public boolean equals(java.lang.Object);
    }
    

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100. public final class Person {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String getName();
     public int getAge();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     // copy and component methods omitted…
     }
     public final class Person extends java.lang.Record {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String name();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     }
     

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101. public java.lang.String getName();
     public int getAge();
     public java.lang.String toString();
     Code:
     0: new #44 // class java/lang/StringBuilder
     3: dup
     4: invokespecial #45 // Method java/lang/StringBuilder."":()V
     7: ldc #47 // String Person(name=
     9: invokevirtual #51 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
     12: aload_0
     13: getfield #11 // Field name:Ljava/lang/String;
     16: invokevirtual #51 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
     19: ldc #53 // String , age=
     21: invokevirtual #51 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
     24: aload_0
     25: getfield #19 // Field age:I
     28: invokevirtual #56 // Method java/lang/StringBuilder.append:(I)Ljava/lang/StringBuilder;
     31: ldc #58 // String )
     33: invokevirtual #51 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
     36: invokevirtual #60 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
     39: areturn
     public int hashCode();
     public boolean equals(java.lang.Object);
     // copy and component methods omitted…
     }
     public final class Person extends java.lang.Record {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String name();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     }
     

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102. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String name();
     public int age();
     public java.lang.String toString();
     Code:
     0: aload_0
     1: invokedynamic #19, 0 // InvokeDynamic #0:toString:(LPerson;)Ljava/lang/String;
     6: areturn
     public int hashCode();
     public boolean equals(java.lang.Object);
     public java.lang.String getName();
     public int getAge();
     public java.lang.String toString();
     Code:
     0: new #44 // class java/lang/StringBuilder
     3: dup
     4: invokespecial #45 // Method java/lang/StringBuilder."":()V
     7: ldc #47 // String Person(name=
     9: invokevirtual #51 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
     12: aload_0
     13: getfield #11 // Field name:Ljava/lang/String;
     16: invokevirtual #51 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
     19: ldc #53 // String , age=
     21: invokevirtual #51 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
     24: aload_0
     25: getfield #19 // Field age:I
     28: invokevirtual #56 // Method java/lang/StringBuilder.append:(I)Ljava/lang/StringBuilder;
     31: ldc #58 // String )
     33: invokevirtual #51 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
     36: invokevirtual #60 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
     39: areturn
     public int hashCode();
     

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103. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String name();
     public int age();
     public java.lang.String toString();
     Code:
     0: aload_0
     1: invokedynamic #19, 0 // InvokeDynamic #0:toString:(LPerson;)Ljava/lang/String;
     6: areturn
     public int hashCode();
     public boolean equals(java.lang.Object);
     }
     

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104. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String name();
     public int age();
     public java.lang.String toString();
     Code:
     0: aload_0
     1: invokedynamic #19, 0 // InvokeDynamic #0:toString:(LPerson;)Ljava/lang/String;
     6: areturn
     public int hashCode();
     public boolean equals(java.lang.Object);
     }
     BootstrapMethods:
     0: #42 REF_invokeStatic java/lang/runtime/ObjectMethods.bootstrap:
     (Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;
     Ljava/lang/invoke/TypeDescriptor;Ljava/lang/Class;Ljava/lang/String;
     [Ljava/lang/invoke/MethodHandle;)Ljava/lang/Object;
     Method arguments:
     #8 Person
     #49 name;age
     #51 REF_getField Person.name:Ljava/lang/String;
     #52 REF_getField Person.age:I
     Code:
     0: aload_0
     1: invokedynamic #23, 0 // InvokeDynamic #0:hashCode:(LPerson;)I
     6: areturn
     

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105. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String name();
     public int age();
     public java.lang.String toString();
     Code:
     0: aload_0
     1: invokedynamic #19, 0 // InvokeDynamic #0:toString:(LPerson;)Ljava/lang/String;
     6: areturn
     public int hashCode();
     public boolean equals(java.lang.Object);
     }
     BootstrapMethods:
     0: #42 REF_invokeStatic java/lang/runtime/ObjectMethods.bootstrap:
     (Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;
     Ljava/lang/invoke/TypeDescriptor;Ljava/lang/Class;Ljava/lang/String;
     [Ljava/lang/invoke/MethodHandle;)Ljava/lang/Object;
     Method arguments:
     #8 Person
     #49 name;age
     #51 REF_getField Person.name:Ljava/lang/String;
     #52 REF_getField Person.age:I
     Code:
     0: aload_0
     1: invokedynamic #23, 0 // InvokeDynamic #0:hashCode:(LPerson;)I
     6: areturn
     

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106. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String name();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     Code:
     0: aload_0
     1: invokedynamic #23, 0 // InvokeDynamic #0:hashCode:(LPerson;)I
     6: areturn
     public boolean equals(java.lang.Object);
     }
     BootstrapMethods:
     0: #42 REF_invokeStatic java/lang/runtime/ObjectMethods.bootstrap:
     (Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;
     Ljava/lang/invoke/TypeDescriptor;Ljava/lang/Class;Ljava/lang/String;
     [Ljava/lang/invoke/MethodHandle;)Ljava/lang/Object;
     Method arguments:
     #8 Person
     #49 name;age
     #51 REF_getField Person.name:Ljava/lang/String;
     #52 REF_getField Person.age:I
     Code:
     0: aload_0
     1: invokedynamic #19, 0 // InvokeDynamic #0:toString:(LPerson;)Ljava/lang/String;
     6: areturn
     

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107. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String name();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     Code:
     0: aload_0
     1: invokedynamic #27, 0 // InvokeDynamic #0:equals:(LPerson;Ljava/lang/Object;)Z
     6: areturn
     }
     BootstrapMethods:
     0: #42 REF_invokeStatic java/lang/runtime/ObjectMethods.bootstrap:
     (Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;
     Ljava/lang/invoke/TypeDescriptor;Ljava/lang/Class;Ljava/lang/String;
     [Ljava/lang/invoke/MethodHandle;)Ljava/lang/Object;
     Method arguments:
     #8 Person
     #49 name;age
     #51 REF_getField Person.name:Ljava/lang/String;
     #52 REF_getField Person.age:I
     Code:
     0: aload_0
     1: invokedynamic #23, 0 // InvokeDynamic #0:hashCode:(LPerson;)I
     6: areturn
     Code:
     0: aload_0
     1: invokedynamic #27, 0 /q InvokeDynamic #0:equals:(LPerson;Ljava/lang/Object;)Z
     6: areturn
     

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108. public final class Person {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String getName();
     public int getAge();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     // copy and component methods omitted…
     }
     public final class Person extends java.lang.Record {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String name();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     }
     Code:
     0: aload_0
     1: invokedynamic #27, 0 // InvokeDynamic #0:equals:(LPerson;Ljava/lang/Object;)Z
     6: areturn
     

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109. data class Person(val name: String, val age: Int)
     record Person(String name, int age) { }
     

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110. data class Person(val name: String, val age: Int)
     record Person(String name, int age) { }
     "Use StringConcatFactory for data class toString when targeting JVM 9+ "
     youtrack.jetbrains.com/issue/KT-35176
     

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111. Sealed Hierarchies
     

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112. data class Person(val name: String, val age: Int)
     

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113. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     

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114. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     record Person(String name, int age) { }
     

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115. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Developer { }
     record Person(String name, int age) extends Developer { }
     record Business(String name) extends Developer { }
     

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116. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     class
     extends
     extends
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     

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117. sealed class Developer {
     abstract val name: String
     }
     data class Person(override val name: String, val age: Int) : Developer()
     data class Business(override val name: String) : Developer()
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     

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118. sealed class Developer {
     abstract val name: String
     }
     data class Person(override val name: String, val age: Int) : Developer()
     data class Business(override val name: String) : Developer()
     sealed interface Developer {
     String name();
     }
     record Person(@Override String name, int age) implements Developer { }
     record Business(@Override String name) implements Developer { }
     

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119. public abstract class Developer {
     public abstract java.lang.String getName();
     private Developer();
     public synthetic Developer(kotlin.jvm.internal.DefaultConstructorMarker);
     }
     public interface Developer {
     public abstract java.lang.String name();
     }
     PermittedSubtypes:
     Person
     Business
     

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120. public abstract class Developer {
     public abstract java.lang.String getName();
     private Developer();
     public synthetic Developer(kotlin.jvm.internal.DefaultConstructorMarker);
     }
     public interface Developer {
     public abstract java.lang.String name();
     }
     PermittedSubtypes:
     Person
     Business
     

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121. public abstract class Developer {
     public abstract java.lang.String getName();
     private Developer();
     public synthetic Developer(kotlin.jvm.internal.DefaultConstructorMarker);
     }
     public interface Developer {
     public abstract java.lang.String name();
     }
     PermittedSubtypes:
     Person
     Business
     

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122. sealed class Developer {
     abstract val name: String
     }
     data class Person(override val name: String, val age: Int) : Developer()
     data class Business(override val name: String) : Developer()
     sealed interface Developer {
     String name();
     }
     record Person(@Override String name, int age) implements Developer { }
     record Business(@Override String name) implements Developer { }
     

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123. Type Matching
     

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124. val o: Any = 1
     

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125. val o: Any = 1
     if (o is Int) {
     }
     

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126. val o: Any = 1
     if (o is Int) {
     println(o + 1)
     }
     

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127. val o: Any = 1
     if (o is Int) {
     println(o + 1)
     }
     Object o = 1;
     if (o instanceof Integer i) {
     System.out.println(i + 1);
     }
     

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128. Object o = 1;
     if (o instanceof Integer i) {
     System.out.println(i + 1);
     }
     

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129. Object o = 1;
     if (o instanceof Integer) {
     Integer i = (Integer) o;
     System.out.println(i + 1);
     }
     

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130. Object o = 1;
     if (o instanceof Integer) {
     Integer i = (Integer) o;
     System.out.println(i + 1);
     }
     static void record(Object o) {
     objects.add(o);
     }
     static void record(Number n) {
     sum += n.intValue();
     }
     

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131. Object o = 1;
     if (o instanceof Integer) {
     Integer i = (Integer) o;
     System.out.println(i + 1);
     record(o);
     }
     static void record(Object o) {
     objects.add(o);
     }
     static void record(Number n) {
     sum += n.intValue();
     }
     

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132. Object o = 1;
     if (o instanceof Integer) {
     System.out.println(o + 1);
     record(o);
     }
     static void record(Object o) {
     objects.add(o);
     }
     static void record(Number n) {
     sum += n.intValue();
     }
     

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133. Object o = 1;
     if (o instanceof Integer) {
     System.out.println(o + 1);
     record(o);
     }
     static void record(Object o) {
     objects.add(o);
     }
     static void record(Number n) {
     sum += n.intValue();
     }
     

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134. Object o = 1;
     if (o instanceof Integer) {
     System.out.println(o + 1);
     record(o);
     }
     static void record(Object o) {
     objects.add(o);
     }
     static void record(Number n) {
     sum += n.intValue();
     }
     

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135. Object o = 1;
     if (o instanceof Integer i) {
     System.out.println(i + 1);
     record(o);
     }
     static void record(Object o) {
     objects.add(o);
     }
     static void record(Number n) {
     sum += n.intValue();
     }
     

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136. val o: Any = 1
     if (o is Int) {
     println(o + 1)
     }
     Object o = 1;
     if (o instanceof Integer i) {
     System.out.println(i + 1);
     }
     record(o);
     static void record(Object o) {
     objects.add(o);
     }
     static void record(Number n) {
     sum += n.intValue();
     

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137. Destructuring
     

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138. data class Person(val name: String, val age: Int)
     

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139. data class Person(val name: String, val age: Int)
     val alice = Person("Alice", 12)
     

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140. data class Person(val name: String, val age: Int)
     val alice = Person("Alice", 12)
     val (name, age) = alice
     

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141. data class Person(val name: String, val age: Int)
     val alice = Person("Alice", 12)
     val (name, age) = alice
     val people = listOf(alice)
     for ((name, age) in people) {
     // ..
     }
     

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142. data class Person(val name: String, val age: Int)
     val alice = Person("Alice", 12)
     val (name, age) = alice
     val people = listOf(alice)
     for ((name, age) in people) {
     // ..
     }
     val display = people.map { (name, age) -> "$name is $age years old" }
     

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143. data class Person(val name: String, val age: Int)
     val alice = Person("Alice", 12)
     val (name, age) = alice
     

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144. data class Person(val name: String, val age: Int)
     val alice = Person("Alice", 12)
     val (name, age) = alice
     

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145. ⋮
     10: aload_0
     11: invokevirtual #12 // Method Person.component1:()Ljava/lang/String;
     14: astore_1
     15: aload_0
     16: invokevirtual #16 // Method Person.component2:()I
     19: istore_2
     ⋮
     

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146. public final class Person {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String getName();
     public int getAge();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     // copy and component methods omitted…
     }
     

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147. public final class Person {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String getName();
     public int getAge();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     // copy methods omitted…
     public java.lang.String component1();
     public int component2();
     }
     a
     n
     d c
     o
     m
     p
     o
     n
     e
     n
     t
     

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148. data class Person(val name: String, val age: Int)
     val alice = Person("Alice", 12)
     val (name, age) = alice
     

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149. data class Person(
     val name: String,
     val nickname: String,
     val age: Int
     )
     val alice = Person("Alice", "Ali", 12)
     val (name, age) = alice
     

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150. public final class Person {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String getName();
     public int getAge();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     // copy methods omitted…
     public java.lang.String component1();
     public int component2();
     }
     

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151. public final class Person {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     - public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String getName();
     + public java.lang.String getNickname();
     public int getAge();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     // copy methods omitted…
     public java.lang.String component1();
     - public int component2();
     + public java.lang.String component2();
     + public int component3();
     }
     

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152. public final class Person {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     - public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String getName();
     + public java.lang.String getNickname();
     public int getAge();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     // copy methods omitted…
     public java.lang.String component1();
     - public int component2();
     + public java.lang.String component2();
     + public int component3();
     }
     

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153. data class Person(val name: String, val age: Int)
     val alice = Person("Alice", 12)
     val (name, age) = alice
     

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154. data class Person(val name: String, val age: Int)
     val alice = Person("Alice", 12)
     val (name, age) = alice
     record Person(String name, int age) { }
     var alice = new Person("Alice", 12);
     

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155. data class Person(val name: String, val age: Int)
     val alice = Person("Alice", 12)
     val (name, age) = alice
     record Person(String name, int age) { }
     Object alice = new Person("Alice", 12);
     

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156. data class Person(val name: String, val age: Int)
     val alice = Person("Alice", 12)
     val (name, age) = alice
     record Person(String name, int age) { }
     Object alice = new Person("Alice", 12);
     if (alice instanceof Person alicePerson) {
     // ...
     }
     

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157. data class Person(val name: String, val age: Int)
     val alice = Person("Alice", 12)
     val (name, age) = alice
     record Person(String name, int age) { }
     Object alice = new Person("Alice", 12);
     if (alice instanceof Person(var name, var age)) {
     // ...
     }
     alicePerson
     

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158. data class Person(val name: String, val age: Int)
     val alice: Any = Person("Alice", 12)
     if (alice is Person) {
     val (name, age) = alice
     // ...
     }
     record Person(String name, int age) { }
     Object alice = new Person("Alice", 12);
     if (alice instanceof Person(var name, var age)) {
     // ...
     }
     

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159. record Person(String name, int age) { }
     Object alice = new Person("Alice", 12);
     if (alice instanceof Person(var name, var age)) {
     // ...
     }
     

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160. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String name();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     }
     

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161. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String name();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     }
     

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162. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String name();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     }
     

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163. record Person(String name, int age) { }
     Object alice = new Person("Alice", 12);
     if (alice instanceof Person(var name, var age)) {
     // ...
     }
     

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164. record Person(String name, String nickname, int age) { }
     Object alice = new Person("Alice", "Ali", 12);
     if (alice instanceof Person(var name, var age)) {
     // ...
     }
     

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165. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     private final int age;
     public Person(java.lang.String, int);
     public java.lang.String name();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     }
     

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166. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     - public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     - public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     + public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?Ljava|lang|String?I)();
     }
     

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167. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     - public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     - public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     + public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?Ljava|lang|String?I)();
     }
     

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168. record Person(String name, String nickname, int age) { }
     

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169. record Person(String name, String nickname, int age) {
     Person(String name, int age) {
     this(name, null, age);
     }
     }
     

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170. record Person(String name, String nickname, int age) {
     Person(String name, int age) {
     this(name, null, age);
     }
     // WARNING: 100% made-up syntax by me!
     destructor Person(String, int) {
     return p -> deconstruct(Person::name, Person::age);
     }
     }
     

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171. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     - public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     - public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     + public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?Ljava|lang|String?I)();
     }
     

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172. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     + public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?Ljava|lang|String?I)();
     }
     

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173. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     data class Person(val name: String, val age: Int)
     val alice: Any = Person("Alice", 12)
     if (alice is Person) {
     val (name, age) = alice
     // ...
     }
     record Person(String name, int age) { }
     Object alice = new Person("Alice", 12);
     if (alice instanceof Person(var name, var age)) {
     // ...
     }
     

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174. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     sealed class Developer
     data class Person(val name: String, val age: Int): Developer()
     data class Business(val name: String): Developer()
     val alice: Any = Person("Alice", 12)
     if (alice is Person) {
     val (name, age) = alice
     // ...
     }
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     Object alice = new Person("Alice", 12);
     if (alice instanceof Person(var name, var age)) {
     // ...
     }
     

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175. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     Object alice = new Person("Alice", 12);
     if (alice instanceof Person(var name, var age)) {
     // ...
     }
     sealed class Developer
     data class Person(val name: String, val age: Int): Developer()
     data class Business(val name: String): Developer()
     val alice: Any = Person("Alice", 12)
     if (alice is Person) {
     val (name, age) = alice
     // ...
     }
     public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     

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176. sealed class Developer
     data class Person(val name: String, val age: Int): Developer()
     data class Business(val name: String): Developer()
     val alice: Developer = Person("Alice", 12)
     if (alice is Person) {
     val (name, age) = alice
     // ...
     }
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     Developer alice = new Person("Alice", 12);
     if (alice instanceof Person(var name, var age)) {
     // ...
     }
     Object
     public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     

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177. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     sealed class Developer
     data class Person(val name: String, val age: Int): Developer()
     data class Business(val name: String): Developer()
     val alice: Developer = Person("Alice", 12)
     if (alice is Person) {
     val (name, age) = alice
     // ...
     }
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     Developer alice = new Person("Alice", 12);
     if (alice instanceof Person(var name, var age)) {
     // ...
     }
     Object
     

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178. sealed class Developer
     data class Person(val name: String, val age: Int): Developer()
     data class Business(val name: String): Developer()
     val alice: Developer = Person("Alice", 12)
     if (alice is Person) {
     val (name, age) = alice
     // ...
     }
     

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179. sealed class Developer
     data class Person(val name: String, val age: Int): Developer()
     data class Business(val name: String): Developer()
     val alice: Developer = Person("Alice", 12)
     when (alice) {
     is Person -> {
     val (name, age) = alice
     // ...
     }
     is Business -> {
     // ...
     }
     }
     if
     

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180. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     + public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?Ljava|lang|String?I)();
     }
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     Developer alice = new Person("Alice", 12);
     if (alice instanceof Person(var name, var age)) {
     // ...
     }
     

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181. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     + public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?Ljava|lang|String?I)();
     }
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     Developer alice = new Person("Alice", 12);
     switch (alice) {
     case Person(var name, var age) -> // ...
     case Business b -> // ...
     }
     if i
     n
     s
     t
     a
     n
     c
     e
     o
     f
     

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182. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     + public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?Ljava|lang|String?I)();
     }
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     Developer alice = new Person("Alice", 12);
     switch (alice) {
     case Person(var name, var age) -> // ...
     case Business b -> // ...
     }
     

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183. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     + public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?Ljava|lang|String?I)();
     }
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     Developer alice = new Person("Alice", 12);
     switch (alice) {
     case Person(var name, var age) -> // ...
     case Business b -> // ...
     }
     

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184. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     + public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?Ljava|lang|String?I)();
     }
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     Developer alice = new Person("Alice", 12);
     switch (alice) {
     case Person(var name, var age) -> // ...
     case Business b -> // ...
     }
     

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185. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     + public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?Ljava|lang|String?I)();
     }
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     Developer alice = new Person("Alice", 12);
     switch (alice) {
     case Person(var name, var age) -> // ...
     case Business b -> // ...
     }
     

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186. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     public java.lang.String toString();
     public int hashCode();
     public boolean equals(java.lang.Object);
     public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?I)();
     + public static java.lang.runtime.PatternHandle
     %pattern%Person%(Ljava|lang|String?Ljava|lang|String?I)();
     }
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     Developer alice = new Person("Alice", 12);
     switch (alice) {
     case Person(var name, var age) -> // ...
     case Business b -> // ...
     }
     

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187. public final class Person extends java.lang.Record {
     private final java.lang.String name;
     + private final java.lang.String nickname;
     private final int age;
     public Person(java.lang.String, int);
     + public Person(java.lang.String, java.lang.String, int);
     public java.lang.String name();
     + public java.lang.String nickname();
     public int age();
     val alice: Developer = Person("Alice", 12)
     when (alice) {
     is Person -> {
     val (name, age) = alice
     // ...
     }
     is Business -> // ...
     }
     Developer alice = new Person("Alice", 12);
     switch (alice) {
     case Person(var name, var age) -> // ...
     case Business b -> // ...
     }
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     

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188. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     

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189. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     

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190. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     

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191. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     val result = if (download is App) {
     }
     

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192. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     val result = if (download is App &&
     download.developer is Person) {
     }
     

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193. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     val result = if (download is App &&
     download.developer is Person &&
     download.developer.name == "Alice") {
     }
     

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194. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     val result = if (download is App &&
     download.developer is Person &&
     download.developer.name == "Alice") {
     "Alice's app ${download.name}"
     }
     

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195. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     val result = if (download is App &&
     download.developer is Person &&
     download.developer.name == "Alice") {
     "Alice's app ${download.name}"
     } else if (download is Movie) {
     }
     

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196. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     val result = if (download is App &&
     download.developer is Person &&
     download.developer.name == "Alice") {
     "Alice's app ${download.name}"
     } else if (download is Movie && download.director.name == "Alice") {
     }
     

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197. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     val result = if (download is App &&
     download.developer is Person &&
     download.developer.name == "Alice") {
     "Alice's app ${download.name}"
     } else if (download is Movie && download.director.name == "Alice") {
     "Alice's movie ${download.title}"
     }
     

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198. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     val result = if (download is App &&
     download.developer is Person &&
     download.developer.name == "Alice") {
     "Alice's app ${download.name}"
     } else if (download is Movie && download.director.name == "Alice") {
     "Alice's movie ${download.title}"
     } else {
     "Not by Alice"
     }
     

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199. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     data class TvShow(val title: String, val showRunner: Person) : Download()
     val download: Download = //...
     val result = if (download is App &&
     download.developer is Person &&
     download.developer.name == "Alice") {
     "Alice's app ${download.name}"
     } else if (download is Movie && download.director.name == "Alice") {
     "Alice's movie ${download.title}"
     } else {
     "Not by Alice"
     }
     

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200. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     

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201. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     val result = when (download) {
     is App ->
     is Movie ->
     }
     

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202. sealed class Developer
     data class Person(val name: String, val age: Int) : Developer()
     data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     val result = when (download) {
     is App ->
     if (download.developer is Person && download.developer.name == "Alice") {
     "Alice's app ${download.name}"
     } else {
     "Not by Alice"
     }
     is Movie ->
     }
     

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203. data class Business(val name: String) : Developer()
     sealed class Download
     data class App(val name: String, val developer: Developer) : Download()
     data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     val result = when (download) {
     is App ->
     if (download.developer is Person && download.developer.name == "Alice") {
     "Alice's app ${download.name}"
     } else {
     "Not by Alice"
     }
     is Movie ->
     if (download.director.name == "Alice") {
     "Alice's movie ${download.title}"
     } else {
     "Not by Alice"
     }
     }
     

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204. data class Movie(val title: String, val director: Person) : Download()
     val download: Download = //...
     val result = when (download) {
     is App ->
     when (download.developer) {
     is Person ->
     if (download.developer.name == "Alice") {
     "Alice's app ${download.name}"
     } else {
     "Not by Alice"
     }
     else -> "Not by Alice"
     }
     is Movie ->
     if (download.director.name == "Alice") {
     "Alice's movie ${download.title}"
     } else {
     "Not by Alice"
     }
     }
     

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205. val result = when (download) {
     is App -> {
     val (name, developer) = download
     when (developer) {
     is Person ->
     if (developer.name == "Alice") {
     "Alice's app $name"
     } else {
     "Not by Alice"
     }
     else -> "Not by Alice"
     }
     }
     is Movie -> {
     val (title, directory) = download
     if (director.name == "Alice") {
     "Alice's movie $title"
     } else {
     "Not by Alice"
     }
     }
     }
     download
     download
     download
     

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206. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     

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207. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     Download download = //...
     

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208. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     Download download = //...
     var result = switch (download) {
     case App ->
     case Movie ->
     };
     

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209. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     Download download = //...
     var result = switch (download) {
     case App ->
     case Movie ->
     };
     

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210. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     Download download = //...
     var result = switch (download) {
     case App ->
     case Movie ->
     };
     

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211. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     Download download = //...
     var result = switch (download) {
     case App(var name, var developer) ->
     case Movie ->
     };
     

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212. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     Download download = //...
     var result = switch (download) {
     case App(var name, var developer) ->
     case Movie ->
     };
     

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213. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     Download download = //...
     var result = switch (download) {
     case App(var name, Person("Alice", _)) ->
     case Movie ->
     };
     var developer
     

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214. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     Download download = //...
     var result = switch (download) {
     case App(var name, Person("Alice", _)) ->
     case Movie ->
     };
     var developer
     

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215. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     Download download = //...
     var result = switch (download) {
     case App(var name, Person("Alice", _)) -> "Alice's app " + name
     case Movie ->
     };
     

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216. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     Download download = //...
     var result = switch (download) {
     case App(var name, Person("Alice", _)) -> "Alice's app " + name
     case Movie(var title, Person("Alice", _)) ->
     };
     

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217. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     Download download = //...
     var result = switch (download) {
     case App(var name, Person("Alice", _)) -> "Alice's app " + name
     case Movie(var title, Person("Alice", _)) -> "Alice's movie " + title
     };
     

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218. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     Download download = //...
     var result = switch (download) {
     case App(var name, Person("Alice", _)) -> "Alice's app " + name
     case Movie(var title, Person("Alice", _)) -> "Alice's movie " + title
     case App(_), Movie(_) -> "Not by Alice"
     };
     

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219. val download: Download = //...
     val result = when (download) {
     is App -> {
     val (name, developer) = download
     when (developer) {
     is Person ->
     if (developer.name == "Alice") {
     "Alice's app $name"
     } else {
     "Not by Alice"
     }
     else -> "Not by Alice"
     }
     }
     is Movie -> {
     val (title, directory) = download
     if (director.name == "Alice") {
     "Alice's movie $title"
     } else {
     "Not by Alice"
     }
     }
     }
     Download download = //...
     var result = switch (download) {
     case App(var name, Person("Alice", _)) -> "Alice's app " + name
     case Movie(var title, Person("Alice", _)) -> "Alice's movie " + title
     case App(_), Movie(_) -> "Not by Alice"
     };
     sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     sealed interface Download { }
     record App(String name, Developer developer) implements Download { }
     record Movie(String title, Person director) implements Download { }
     

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220. Coroutines
     

     View Slide

221. suspend fun main() = coroutineScope {
     for (count in 10 downTo 0) {
     launch {
     delay(100.milliseconds * count)
     println(count)
     }
     }
     }
     

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222. suspend fun main() = coroutineScope {
     for (count in 10 downTo 0) {
     launch {
     delay(100.milliseconds * count)
     println(count)
     }
     }
     }
     

     

     

     

     

     

     

     

     

     

     0
     1
     2
     3
     4
     5
     6
     7
     8
     9
     10
     

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223. suspend fun main() = coroutineScope {
     for (count in 10 downTo 0) {
     launch {
     delay(100.milliseconds * count)
     println(count)
     }
     }
     }
     

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224. suspend fun main() = coroutineScope {
     for (count in 10 downTo 0) {
     launch {
     delay(100.milliseconds * count)
     println(count)
     }
     }
     }
     

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225. suspend fun main() = coroutineScope {
     for (count in 10 downTo 0) {
     launch {
     delay(100.milliseconds * count)
     println(count)
     }
     }
     }
     

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226. suspend fun main() = coroutineScope {
     for (count in 10 downTo 0) {
     launch {
     delay(100.milliseconds * count)
     println(count)
     }
     }
     }
     public static void main(String... args) {
     Executor e = Executors.newWorkStealingPool();
     for (int count = 10; count >= 0; count--) {
     final var finalCount = count;
     e.execute(() -> {
     Thread.sleep(100 * finalCount);
     System.out.println(finalCount);
     });
     }
     }
     

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227. suspend fun main() = coroutineScope {
     for (count in 10 downTo 0) {
     launch {
     delay(100.milliseconds * count)
     println(count)
     }
     }
     }
     public static void main(String... args) {
     Executor e = Executors.newWorkStealingPool();
     for (int count = 10; count >= 0; count--) {
     final var finalCount = count;
     e.execute(() -> {
     Thread.sleep(100 * finalCount);
     System.out.println(finalCount);
     });
     }
     }
     

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228. suspend fun main() = coroutineScope {
     for (count in 10 downTo 0) {
     launch {
     delay(100.milliseconds * count)
     println(count)
     }
     }
     }
     public static void main(String... args) {
     Executor e = Executors.newWorkStealingPool();
     for (int count = 10; count >= 0; count--) {
     final var finalCount = count;
     e.execute(() -> {
     Thread.sleep(100 * finalCount);
     System.out.println(finalCount);
     });
     }
     }
     

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229. The end of Kotlin?
     

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230. var count = 1
     final var users = new ArrayList()
     The end of Kotlin?
     Java 10: Variable Type Inference
     

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231. public static boolean any(Predicate predicate) {
     var seen = new HashSet();
     boolean hasMatch(Node node) {
     if (!seen.add(node)) return false; // already seen
     if (predicate.test(node)) return true; // match!
     return node.getNodes().stream().anyMatch(n -> hasMatch(n));
     }
     return hasMatch(getRoot());
     }
     Java 16/17: Local Methods
     

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232. public static void main(String[] args) {
     System.out.println("""
     SELECT *
     FROM users
     WHERE name LIKE 'Jake %'
     """);
     }
     Java 15: Multiline Strings
     

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233. record Person(String name, int age) { }
     Java 15/16: Records
     

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234. sealed interface Developer { }
     record Person(String name, int age) implements Developer { }
     record Business(String name) implements Developer { }
     Java 15/16: Sealed Hierarchies
     

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235. Object o = 1;
     if (o instanceof Integer i) {
     System.out.println(i + 1);
     }
     Java 15/16: Type Matching
     

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236. Download download = //...
     var result = switch (download) {
     case App(var name, Person("Alice", _)) -> "Alice's app " + name
     case Movie(var title, Person("Alice", _)) -> "Alice's movie " + title
     case App(_), Movie(_) -> "Not by Alice"
     };
     Java 16/17: Pattern Matching
     

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237. Download download = //...
     var result = switch (download) {
     case App(var name, Person("Alice", _)) -> "Alice's app " + name
     case Movie(var title, Person("Alice", _)) -> "Alice's movie " + title
     case App(_), Movie(_) -> "Not by Alice"
     };
     Java 14: Expression Switch
     

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238. public static void main(String... args) {
     Executor e = Executors.newWorkStealingPool();
     for (int count = 10; count >= 0; count--) {
     final var finalCount = count;
     e.execute(() -> {
     Thread.sleep(100 * finalCount);
     System.out.println(finalCount);
     });
     }
     }
     Java 16/17: Virtual Threads
     

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239. The end of Kotlin?
     New Java APIs and new VM improvements also help Kotlin
     

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240. The end of Kotlin?
     New Java APIs and new VM improvements also help Kotlin
     API, bytecode, and VM changes for new Java language features are
     also available for use by kotlinc
     

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241. The end of Kotlin?
     New Java APIs and new VM improvements also help Kotlin
     API, bytecode, and VM changes for new Java language features are
     also available for use by kotlinc
     No plans to tackle nullability in Java!
     

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242. The end of Kotlin?
     New Java APIs and new VM improvements also help Kotlin
     API, bytecode, and VM changes for new Java language features are
     also available for use by kotlinc
     No plans to tackle nullability in Java!
     Java in 3 years will also be competing with Kotlin in 3 years,

     not the Kotlin of today
     

     View Slide

243. The end of Kotlin?
     New Java APIs and new VM improvements also help Kotlin
     API, bytecode, and VM changes for new Java language features are
     also available for use by kotlinc
     No plans to tackle nullability in Java!
     Java in 3 years will also be competing with Kotlin in 3 years,

     not the Kotlin of today
     Kotlin has an IDE to potentially evolve in ways that Java cannot
     

     View Slide

244. The end of Kotlin?
     New Java APIs and new VM improvements also help Kotlin
     API, bytecode, and VM changes for new Java language features are
     also available for use by kotlinc
     No plans to tackle nullability in Java!
     Java in 3 years will also be competing with Kotlin in 3 years,

     not the Kotlin of today
     Kotlin has an IDE to potentially evolve in ways that Java cannot
     Kotlin has first-class multiplatform
     

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245. What's new in Java 19:
     The end of Kotlin?
     @JakeWharton
     [ Nope! ]
     

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