Top 10 Kotlin Stack Overflow Questions (Kotlin Budapest User Group meetup - May)

A selection of some of the most frequent questions about Kotlin on Stack Overflow, asked, answered and explained. Something in there for everyone, from beginners to experts.

Transcript

1. TOP 10 KOTLIN STACK OVERFLOW QUESTIONS Márton Szabolcs Braun zsmb.co zsmb13 braun.marton@autsoft.hu
2. Why do this talk?
3. Why do this talk?
4. Array<Int> vs IntArray What’s the difference? When do I use which one?
5. Array<Int> vs IntArray
6. Array<Int> vs IntArray Array<Int>
7. Array<Int> vs IntArray Array<Int> Integer[]
8. Array<Int> vs IntArray Array<Int> Integer[] val arrayOfInts: Array<Int> = arrayOf(1, 2, 3, 4, 5)
9. Array<Int> vs IntArray Array<Int> Integer[] IntArray val arrayOfInts: Array<Int> = arrayOf(1, 2, 3, 4, 5)
10. Array<Int> vs IntArray Array<Int> Integer[] IntArray int[] val arrayOfInts: Array<Int> = arrayOf(1, 2, 3, 4, 5)
11. Array<Int> vs IntArray Array<Int> Integer[] IntArray int[] val intArray: IntArray = intArrayOf(1, 2, 3, 4, 5) val arrayOfInts: Array<Int> = arrayOf(1, 2, 3, 4, 5)
12. Array<Int> vs IntArray
13. Array<Int> vs IntArray • IntArray
14. Array<Int> vs IntArray • IntArray  Avoids boxing
15. Array<Int> vs IntArray • IntArray  Avoids boxing  Easier to initialize val intArray = IntArray(10) val arrayOfInts = Array<Int>(5) { i -> i * 2 }
16. Array<Int> vs IntArray • IntArray  Avoids boxing  Easier to initialize • Array<Int> val intArray = IntArray(10) val arrayOfInts = Array<Int>(5) { i -> i * 2 }
17. Array<Int> vs IntArray • IntArray  Avoids boxing  Easier to initialize • Array<Int>  Might be required by an API val intArray = IntArray(10) val arrayOfInts = Array<Int>(5) { i -> i * 2 }
18. Array<Int> vs IntArray • IntArray  Avoids boxing  Easier to initialize • Array<Int>  Might be required by an API  Can store nullable values val intArray = IntArray(10) val arrayOfInts = Array<Int>(5) { i -> i * 2 } val notPeople: Array<Person?> = arrayOfNulls<Person>(13)
19. Iterable vs Sequence What’s the difference? When do I use which one?
20. Iterable vs Sequence
21. Iterable vs Sequence Iterable
22. Iterable vs Sequence Iterable java.lang.Iterable
23. Iterable vs Sequence  Eager evaluation Iterable java.lang.Iterable
24. Iterable vs Sequence  Eager evaluation Iterable java.lang.Iterable val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5)
25. Iterable vs Sequence
26. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
27. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
28. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
29. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
30. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
31. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
32. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
33. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
34. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
35. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
36. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
37. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
38. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
39. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
40. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
41. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
42. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
43. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
44. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
45. val people: List<Person> = getPeople() val allowedEntrance = people .filter { it.age >= 21 } .map { it.name } .take(5) Iterable vs Sequence
46. Iterable vs Sequence
47. Iterable vs Sequence Sequence
48. Iterable vs Sequence Sequence  Lazy evaluation
49. Iterable vs Sequence Sequence  Lazy evaluation val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
50. Iterable vs Sequence Sequence  Lazy evaluation val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
51. Iterable vs Sequence
52. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
53. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
54. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
55. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
56. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
57. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
58. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
59. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
60. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
61. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
62. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
63. Iterable vs Sequence val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList() val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
64. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
65. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
66. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
67. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
68. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
69. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
70. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
71. Iterable vs Sequence val people: List<Person> = getPeople() val allowedEntrance = people.asSequence() .filter { it.age >= 21 } .map { it.name } .take(5) .toList()
72. Iterable vs Sequence Sequence  Lazy evaluation
73. Iterable vs Sequence Sequence  Lazy evaluation  Potentially infinite
74. Iterable vs Sequence Sequence  Lazy evaluation  Potentially infinite generateSequence(1) { n -> n * 2 } .take(20) .forEach(::println)
75. Iterable vs Sequence
76. Iterable vs Sequence • Iterable
77. Iterable vs Sequence • Iterable  Use by default
78. Iterable vs Sequence • Iterable  Use by default  Usually the best choice
79. Iterable vs Sequence • Iterable  Use by default  Usually the best choice • Sequence
80. Iterable vs Sequence • Iterable  Use by default  Usually the best choice • Sequence  To handle an infinite number of elements
81. Iterable vs Sequence • Iterable  Use by default  Usually the best choice • Sequence  To handle an infinite number of elements  For huge collections, judiciously
82. Iterable vs Sequence • Iterable  Use by default  Usually the best choice • Sequence  To handle an infinite number of elements  For huge collections, judiciously • Stream
83. Iterable vs Sequence • Iterable  Use by default  Usually the best choice • Sequence  To handle an infinite number of elements  For huge collections, judiciously • Stream  When interoperating with Java
84. Iteration How can / should I iterate over collections?
85. Iteration
86. Iteration for (i in 0..args.size - 1) { println(args[i]) }
87. Iteration for (i in 0..args.size - 1) { println(args[i]) } for (i in 0..args.lastIndex) { println(args[i]) }
88. Iteration for (i in 0..args.size - 1) { println(args[i]) } for (i in 0..args.lastIndex) { println(args[i]) } for (i in 0 until args.size) { println(args[i]) }
89. Iteration for (i in 0..args.size - 1) { println(args[i]) } for (i in 0..args.lastIndex) { println(args[i]) } for (i in 0 until args.size) { println(args[i]) } for (i in args.indices) { println(args[i]) }
90. Iteration for (i in 0..args.size - 1) { println(args[i]) } for (i in 0..args.lastIndex) { println(args[i]) } for (i in 0 until args.size) { println(args[i]) } for (i in args.indices) { println(args[i]) } for (arg in args) { println(arg) }
91. Iteration for (i in 0..args.size - 1) { println(args[i]) } for (i in 0..args.lastIndex) { println(args[i]) } for (i in 0 until args.size) { println(args[i]) } for (i in args.indices) { println(args[i]) } for (arg in args) { println(arg) } args.forEach { arg -> println(arg) }
92. Iteration for (i in 0..args.size - 1) { println(args[i]) } for (i in 0..args.lastIndex) { println(args[i]) } for (i in 0 until args.size) { println(args[i]) } for (i in args.indices) { println(args[i]) } for (arg in args) { println(arg) } args.forEach { arg -> println(arg) }
93. Iteration for (i in 0..args.size - 1) { println(args[i]) } for (i in 0..args.lastIndex) { println(args[i]) } for (i in 0 until args.size) { println(args[i]) } for (i in args.indices) { println(args[i]) } for (arg in args) { println(arg) } args.forEach { arg -> println(arg) }
94. Iteration with indexes How can I get both the current index and element?
95. Iteration with indexes for ((index, arg) in args.withIndex()) { println("$index: $arg") }
96. Iteration with indexes for ((index, arg) in args.withIndex()) { println("$index: $arg") } args.forEachIndexed { index, arg -> println("$index: $arg") }
97. Iteration with indexes for ((index, arg) in args.withIndex()) { println("$index: $arg") } args.forEachIndexed { index, arg -> println("$index: $arg") }
98. Iteration with indexes for ((index, arg) in args.withIndex()) { println("$index: $arg") } args.forEachIndexed { index, arg -> println("$index: $arg") }
99. SAM conversions What are SAM conversions?
100. SAM conversions
101. SAM conversions public interface OnClickListener { void onClick(Button button); }
102. SAM conversions public interface OnClickListener { void onClick(Button button); } public class Button { public void setListener(OnClickListener listener) { ... } }
103. SAM conversions
104. SAM conversions button.setListener(object : OnClickListener { override fun onClick(button: Button?) { println("Clicked!") } })
105. SAM conversions button.setListener(object : OnClickListener { override fun onClick(button: Button?) { println("Clicked!") } }) button.setListener { println("Clicked!") }
106. SAM conversions button.setListener(object : OnClickListener { override fun onClick(button: Button?) { println("Clicked!") } }) button.setListener { println("Clicked!") }
107. SAM conversions button.setListener(object : OnClickListener { override fun onClick(button: Button?) { println("Clicked!") } }) button.setListener { button: Button? -> println("Clicked!") }
108. SAM conversions #1 Why are my listeners not being called?
109. SAM conversions #1 button.setListener { object : OnClickListener { override fun onClick(button: Button) { println("Clicked!") } }) }
110. SAM conversions #1 button.setListener { object : OnClickListener { override fun onClick(button: Button) { println("Clicked!") } }) }
111. SAM conversions #1 button.setListener(object : OnClickListener { override fun onClick(button: Button?) { object : OnClickListener { override fun onClick(button: Button) { println("Clicked!") } }) } })
112. SAM conversions #1 button.setListener(object : OnClickListener { override fun onClick(button: Button?) { val listener = object : OnClickListener { override fun onClick(button: Button) { println("Clicked!") } }) } })
113. SAM conversions #1 button.setListener(object : OnClickListener { override fun onClick(button: Button?) { val listener = object : OnClickListener { override fun onClick(button: Button) { println("Clicked!") } }) listener.onClick(...) } })
114. SAM conversions #1 button.setListener(object : OnClickListener { override fun onClick(button: Button?) { object : OnClickListener { override fun onClick(button: Button) { println("Clicked!") } }) } })
115. SAM conversions #1 button.setListener { object : OnClickListener { override fun onClick(button: Button) { println("Clicked!") } }) }
116. SAM conversions #1 button.setListener { object : OnClickListener { override fun onClick(button: Button) { println("Clicked!") } }) } button.setListener { fun onClick(button: Button) { println("Clicked!") } }
117. SAM conversions #2 How do I reference my listener instance?
118. SAM conversions #2 • What if I need to reference the listener instance? button.setListener { button.removeListener(this) }
119. SAM conversions #2 • What if I need to reference the listener instance? button.setListener(object: OnClickListener { override fun onClick(button: Button) { button.removeListener(this) } }) button.setListener { button.removeListener(this) }
120. SAM conversions #3 Why am I getting a return type error?
121. SAM conversions #3 public interface OnClickListener { void onClick(Button button); }
122. SAM conversions #3 public interface OnClickListener { boolean onClick(Button button); }
123. SAM conversions #3 public interface OnClickListener { boolean onClick(Button button); } button.setListener { println("Clicked!") }
124. SAM conversions #3 public interface OnClickListener { boolean onClick(Button button); } button.setListener { println("Clicked!") } Kotlin: Type mismatch: inferred type is Unit but Boolean was expected
125. SAM conversions #3 public interface OnClickListener { boolean onClick(Button button); } button.setListener { println("Clicked!") true }
126. SAM conversions #3 public interface OnClickListener { boolean onClick(Button button); } button.setListener { println("Clicked!") true }
127. SAM conversions #4 What if my interface/method is not written in Java?
128. SAM conversions #4 • SAM constructor button.setListener(OnClickListener { println("Clicked!") })
129. SAM conversions #4 • SAM constructor button.setListener(OnClickListener { println("Clicked!") }) Java interface Kotlin interface Java method SAM conversion Object expression Kotlin method SAM constructor Object expression
130. Replacing statics #1 How do I create static functions and variables in Kotlin?
131. Replacing statics class Foo { companion object { fun x() { ... } } fun y() { ... } }
132. Replacing statics class Foo { companion object { fun x() { ... } } fun y() { ... } } Foo.x()
133. Replacing statics class Foo { companion object { fun x() { ... } } fun y() { ... } } object Foo { fun x() { ... } } Foo.x() Foo.x()
134. Replacing statics class Foo { companion object { fun x() { ... } } fun y() { ... } } object Foo { fun x() { ... } } fun x() { ... } Foo.x() Foo.x() x()
135. Replacing statics class Foo { companion object { fun x() { ... } } fun y() { ... } } object Foo { fun x() { ... } } fun x() { ... } Foo.x() Foo.x() x()
136. Function declaration reference Declaration Kotlin usage Java usage Companion object Foo.f() Foo.Companion.f(); Companion object with @JvmStatic Foo.f() Foo.f(); Object Foo.f() Foo.INSTANCE.f(); Object with @JvmStatic Foo.f() Foo.f(); Top level function f() UtilKt.f(); Top level function with @JvmName* f() Util.f(); * With the @JvmName annotation on the file use-site target
137. Variable declaration reference Declaration Kotlin usage Java usage Companion object X.x X.Companion.getX(); Companion object with @JvmStatic X.x X.getX(); Companion object with @JvmField X.x X.x; Companion object with const X.x X.x; Object X.x X.INSTANCE.getX(); Object with @JvmStatic X.x X.getX(); Object with @JvmField X.x X.x; Object with const X.x X.x; Top level variable x ConstKt.getX(); Top level variable with @JvmField x ConstKt.x; Top level variable with const x ConstKt.x; Top level variable with @JvmName* x Const.getX(); Top level variable with @JvmName* and @JvmField x Const.x; Top level variable with @JvmName* and const x Const.x; * With the @JvmName annotation on the file use-site target
138. Replacing statics #2 What about static initializers?
139. Static initializers class X { companion object { init { println("Static initialization!") } } }
140. Smart casts on mutable properties Why are smart casts not working?
141. Smart casts on mutable properties class Dog(var toy: Toy? = null) { fun play() { if (toy != null) { toy.chew() } } }
142. Smart casts on mutable properties class Dog(var toy: Toy? = null) { fun play() { if (toy != null) { toy.chew() } } } Kotlin: Smart cast to 'Toy' is impossible, because 'toy' is a mutable property that could have been changed by this time
143. Smart casts on mutable properties class Dog(val toy: Toy? = null) { fun play() { if (toy != null) { toy.chew() } } }
144. Smart casts on mutable properties class Dog(var toy: Toy? = null) { fun play() { if (toy != null) { toy.chew() } } }
145. Smart casts on mutable properties class Dog(var toy: Toy? = null) { fun play() { val _toy = toy if (_toy != null) { _toy.chew() } } }
146. Smart casts on mutable properties class Dog(var toy: Toy? = null) { fun play() { toy?.let { it.chew() } } }
147. Smart casts on mutable properties class Dog(var toy: Toy? = null) { fun play() { toy?.chew() } }
148. Smart casts on mutable properties class Dog(var toy: Toy? = null) { fun play() { toy?.let { it.chew() it.chew() it.chew() } } }
149. null!! Why am I getting NullPointerExceptions?
150. null!!
151. null!! class Episode { var airdate: Date = null!! }
152. null!! class Episode { var airdate: Date = null!! } fun getWeekDay(date: Date?): WeekDay { return date!!.getWeekDay() }
153. null!! class Episode { var airdate: Date = null!! } fun getWeekDay(date: Date?): WeekDay { return date!!.getWeekDay() } Date?
154. null!! class Episode { var airdate: Date = null!! } fun getWeekDay(date: Date?): WeekDay { return date!!.getWeekDay() } WeekDay Date?
155. null!! class Episode { var airdate: Date = null!! } fun getWeekDay(date: Date?): WeekDay { return date!!.getWeekDay() } Date WeekDay Date?
156. null!! class Episode { var airdate: Date = null!! } fun getWeekDay(date: Date?): WeekDay { return date!!.getWeekDay() } Date
157. null!! class Episode { var airdate: Date = null!! } fun getWeekDay(date: Date?): WeekDay { return date!!.getWeekDay() } Date date as Date
158. null!! class Episode { var airdate: Date = null!! } fun getWeekDay(date: Date?): WeekDay { return date!!.getWeekDay() } Date date as Date throw NullPointerException()
159. null!! class Episode { var airdate: Date = null!! } fun getWeekDay(date: Date?): WeekDay { return date!!.getWeekDay() } Date
160. null!! class Episode { var airdate: Date = null!! }
161. null!! class Episode { var airdate: Date = null!! }
162. null!! class Episode { var airdate: Date = throw KotlinNullPointerException() }
163. null!! class Episode { lateinit var airdate: Date }
164. Platform types in overrides How do I choose the right type when overriding Java methods?
165. Platform types in overrides
166. Platform types in overrides public interface OnClickListener { void onClick(Button button); }
167. Platform types in overrides public interface OnClickListener { void onClick(Button button); } class KtListener : OnClickListener { override fun onClick(button: Button?): Unit { val name = button?.name ?: "Unknown button" println("Clicked ${name}") } }
168. Platform types in overrides public interface OnClickListener { void onClick(Button button); } class KtListener : OnClickListener { override fun onClick(button: Button?): Unit { val name = button?.name ?: "Unknown button" println("Clicked ${name}") } }
169. Platform types in overrides public interface OnClickListener { void onClick(Button button); } class KtListener : OnClickListener { override fun onClick(button: Button?): Unit { val name = button?.name ?: "Unknown button" println("Clicked ${name}") } }
170. Platform types in overrides public interface OnClickListener { void onClick(Button button); } class KtListener : OnClickListener { override fun onClick(button: Button): Unit { val name = button.name println("Clicked ${name}") } }
171. Import aliases What can I do about imports with conflicting names?
172. Import aliases
173. Import aliases package com.example.code fun indent(str: String) : String { ... } package com.example.square fun indent(str: String) : String { ... }
174. Import aliases package com.example.code fun indent(str: String) : String { ... } package com.example.square fun indent(str: String) : String { ... } import com.example.code.indent indent("hello") com.example.square.indent("world")
175. Import aliases package com.example.code fun String.indent() : String { ... } package com.example.square fun String.indent() : String { ... }
176. Import aliases package com.example.code fun String.indent() : String { ... } package com.example.square fun String.indent() : String { ... } import com.example.code.indent "hello".indent() "world".indent()
177. Import aliases package com.example.code fun String.indent() : String { ... } package com.example.square fun String.indent() : String { ... } import com.example.code.indent as indent4 import com.example.square.indent as indent2 "hello".indent4() "world".indent2()
178. Import aliases import java.util.Date as UtilDate import java.sql.Date as SqlDate fun matches(date1: UtilDate, date2: SqlDate): Boolean { ... }
179. Kotlin vs Java for Android development Please help I just started
180. Kotlin vs Java for Android development
181. Kotlin vs Java for Android development
182. Recap • 1. Array<Int> vs IntArray • 2. Iterable vs Sequence • 3. Iteration (with indexes) • 4. SAM conversions • 5. Replacing statics • 6. Smart casts on mutable properties • 7. null!! • 8. Platform types in overrides • 9. Import aliases • 10. Kotlin vs Java for Android development
183. References • Top 10 Kotlin Stack Overflow questions, article series  https://zsmb.co/top-10-kotlin-stack-overflow-questions-1/ • Kotlin tag on Stack Overflow  https://stackoverflow.com/questions/tagged/kotlin
184. Photo: Alexey Sergeev Questions? zsmb.co zsmb13 braun.marton@autsoft.hu