Collections in Kotlin

5-minute talk about collections in Kotlin

Transcript

1. designing & developing for mobile Demoday, 05/03/2018 Harri Kirik, engineer Kotlin: Collections
2. Kotlin KOTLIN: COLLECTIONS #kotlin
3. Mutable and immutable KOTLIN: COLLECTIONS #collections
4. Autogenerated: 1. equals()/hashCode() pair 2. toString() 3. componentN() functions 4. copy() function KOTLIN: COLLECTIONS #collections
5. KOTLIN: COLLECTIONS val numbers: MutableList<Int> = mutableListOf(1, 2, 3) val readOnlyView: List<Int> = numbers println(numbers) // prints "[1, 2, 3]" numbers.add(4) println(readOnlyView) // prints "[1, 2, 3, 4]" readOnlyView.clear() // -> does not compile val strings = hashSetOf("a", "b", "c", "c") assert(strings.size == 3) #demoday
6. No dedicated syntax KOTLIN: COLLECTIONS #collections
7. listOf(), mutableListOf(), setOf(), mutableSetOf() KOTLIN: COLLECTIONS #collections
8. KOTLIN: COLLECTIONS val mutable = mutableListOf(1, 2, 3) val snapshot = mutable.toList() mutable.add(4) println(mutable) // prints "[1, 2, 3, 4]" println(snapshot) // prints "[1, 2, 3]" #demoday
9. KOTLIN: COLLECTIONS val mutable = mutableListOf(1, 2, 3) val snapshot = mutable.toList() snapshot.add(4) // Will not compile! val snapshot2 = snapshot.plus(4) // Returns a new list println(snapshot2 ) // prints "[1, 2, 3, 4]" #demoday
10. http:// lab.mobi designing & developing for mobile thanks Questions?