Is Kotlin Right For You? - Lead Dev Austin 2018

A Lightning Talk version of "Is Kotlin Right For You?" I gave this talk at The Lead Developer - Austin 2018. It is intended for an audience that knows how to program, but perhaps not in Java or Kotlin. It goes over the top level features and design philosophy of Kotlin.

Transcript

1. Is Kotlin
   Right For You?
   The Lead Developer Austin - 2018
   2018-12-06
   Todd Ginsberg
   @ToddGinsberg
   Principal Software Developer
   

   View Slide

2. @ToddGinsberg
   Questions?
   Office Hours
   11:20
   

   View Slide

3. @ToddGinsberg
   What Is Kotlin?
   

   View Slide

4. @ToddGinsberg
   What Is Kotlin?
   Statically typed language, developed by JetBrains
   Released under Apache 2.0 license
   Designed as a general purpose language
   • Targets JVM 6 or 8 bytecode
   • Targets ECMAScript 5.1
   • Targets native thanks to LLVM (Beta!)
   

   View Slide

5. @ToddGinsberg
   Major Features
   Designed to avoid entire classes of defects
   Null-safe
   178,000+ issues on GitHub!
   12,543 duplicates on Stack Overflow!
   100% Interoperable with Java
   Pragmatic – No shame in copying language features that
   make developers more productive
   

   View Slide

6. @ToddGinsberg
   Make “Bad” Choices Explicit or Impossible
   Fixed in Kotlin:
   - Singleton support built in
   - Override keyword mandatory
   - Properties over fields with getter/setter
   - Mutability is minimized (val + collections)
   - Inheritance prohibited by default
   - Builders are easy with default values
   - No checked exceptions
   - Structural equality is the same everywhere
   - Delegation support makes composition easier
   

   View Slide

7. @ToddGinsberg
   Am I Alone?
   

   View Slide

8. @ToddGinsberg
   Recommended on Android
   Beep! Prefer
   Kotlin over Java!
   - Google I/O 2018
   

   View Slide

9. @ToddGinsberg
   Spring Framework Support
   Kotlin is fully supported in Spring Framework 5
   Kotlin is an option on start.spring.io
   Comprehensive Kotlin documentation and examples
   

   View Slide

10. @ToddGinsberg
    Syntax
    

    View Slide

11. @ToddGinsberg
    Variables and Values
    var place: String = "Chicago"
    place = ”Austin" // OK!
    val name: String = "Todd"
    name = "Emma" // Compile Error!
    

    View Slide

12. @ToddGinsberg
    Inferred Types
    var place: String = "Chicago"
    place = ”Austin" // OK!
    val name: String = "Todd"
    name = "Emma" // Compile Error!
    

    View Slide

13. @ToddGinsberg
    Inferred Types
    var place = "Chicago"
    place = ”Austin" // OK!
    val name = "Todd"
    name = "Emma" // Compile Error!
    

    View Slide

14. @ToddGinsberg
    Null Safety
    // Guaranteed to never be null
    val name: String = "Todd"
    // May be null
    var city: String? = null
    // Safe traversal
    city?.toUpperCase()
    

    View Slide

15. @ToddGinsberg
    Combine Safe-Traversal and Elvis
    println(
    city?.toUpperCase() ?: ”UNKNOWN”
    )
    

    View Slide

16. @ToddGinsberg
    When > Switch
    val result = when(x) {
    0 -> "x is 0”
    in 1..10 -> "x is between 1 and 10”
    in someSet -> "x is in someSet”
    parseString(s) -> "the same as parseString”
    else -> "x doesn't match anything"
    }
    

    View Slide

17. @ToddGinsberg
    Let’s Write a POJO!
    public class Person {
    public String firstName;
    public String lastName;
    }
    

    View Slide

18. @ToddGinsberg
    Let’s Write a POJO!
    public class Person {
    private String firstName;
    private String lastName;
    public String getFirstName() {
    return firstName;
    }
    public void setFirstName(final String firstName) {
    this.firstName = firstName;
    }
    public String getLastName() {
    return lastName;
    }
    public void setLastName(final String lastName) {
    this.lastName = lastName;
    }
    }
    

    View Slide

19. @ToddGinsberg
    Let’s Write a POJO!
    public class Person {
    private String firstName;
    private String lastName;
    public Person() { }
    public Person(final String firstName, final String lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
    }
    public String getFirstName() {
    return firstName;
    }
    public void setFirstName(final String firstName) {
    this.firstName = firstName;
    }
    public String getLastName() {
    return lastName;
    }
    public void setLastName(final String lastName) {
    this.lastName = lastName;
    }
    }
    

    View Slide

20. @ToddGinsberg
    Let’s Write a POJO!
    import java.util.Objects;
    public class Person {
    private String firstName;
    private String lastName;
    public Person() { }
    public Person(final String firstName, final String lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
    }
    public String getFirstName() {
    return firstName;
    }
    public void setFirstName(final String firstName) {
    this.firstName = firstName;
    }
    public String getLastName() {
    return lastName;
    }
    public void setLastName(final String lastName) {
    this.lastName = lastName;
    }
    @Override
    public boolean equals(final Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    final Person person = (Person) o;
    return Objects.equals(firstName, person.firstName) &&
    Objects.equals(lastName, person.lastName);
    }
    @Override
    public int hashCode() {
    return Objects.hash(firstName, lastName);
    }
    }
    

    View Slide

21. @ToddGinsberg
    Let’s Write a POJO!
    import java.util.Objects;
    public class Person {
    private String firstName;
    private String lastName;
    public Person() { }
    public Person(final String firstName, final String lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
    }
    public String getFirstName() {
    return firstName;
    }
    public void setFirstName(final String firstName) {
    this.firstName = firstName;
    }
    public String getLastName() {
    return lastName;
    }
    public void setLastName(final String lastName) {
    this.lastName = lastName;
    }
    @Override
    public boolean equals(final Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    final Person person = (Person) o;
    return Objects.equals(firstName, person.firstName) &&
    Objects.equals(lastName, person.lastName);
    }
    @Override
    public int hashCode() {
    return Objects.hash(firstName, lastName);
    }
    @Override
    public String toString() {
    return "Person{" +
    "firstName='" + firstName + '\'' +
    ", lastName='" + lastName + '\'' +
    '}';
    }
    }
    

    View Slide

22. @ToddGinsberg
    Data Classes To The Rescue!
    data class Person(var firstName: String,
    var lastName: String)
    • toString()
    • hashCode() and equals()
    • Getters and Setters as Properties
    • Copy constructors
    

    View Slide

23. @ToddGinsberg
    Extension FUNctions
    // Java
    public static boolean isEven(int i) {
    return i % 2 == 0;
    }
    // Kotlin
    fun Int.isEven(): Boolean = this % 2 == 0
    2.isEven() // True!
    

    View Slide

24. @ToddGinsberg
    Little Things Add Up
    // No 'new' keyword
    val p = Person("Todd", "Ginsberg")
    // Simple Structural Equality
    "A String" == "A String"
    42 == 42
    

    View Slide

25. @ToddGinsberg
    Little Things Add Up
    // String interpolation
    val d = 2
    println("Todd has $d doughnuts!")
    // Raw string support
    """
    {
    "name": "Todd"
    }
    """
    

    View Slide

26. @ToddGinsberg
    Community
    

    View Slide

27. @ToddGinsberg
    Community Resources
    https://kotlinlang.slack.com
    • 19,500+ welcoming and helpful members
    • Language designers hang out here
    • Get answers and chat with people who work with the
    language
    

    View Slide

28. @ToddGinsberg
    Fun == Fun
    Kotlin
    Thanks, Stack Overflow!
    

    View Slide

29. @ToddGinsberg
    Summary
    

    View Slide

30. @ToddGinsberg
    Learn More
    https://play.kotlinlang.org
    

    View Slide

31. @ToddGinsberg
    Why Kotlin is Right For Me
    I write far less code.
    The code I write is more expressive and clear.
    I avoid whole classes of defects.
    Writing Kotlin, for me, is more fun.
    Plays well with the tools I already use (Spring, IDEA, Gradle)
    

    View Slide

32. @ToddGinsberg
    Is Kotlin is Right For You?
    

    View Slide

33. Than You!
    @ToddGinsberg
    https://todd.ginsberg.com
    todd@ginsberg.com
    

    View Slide