designing & developing for mobile Demoday, 05/03/2018 Harri Kirik, engineer Kotlin: Collections 

Kotlin KOTLIN: COLLECTIONS #kotlin 

Mutable and immutable KOTLIN: COLLECTIONS #collections 

Autogenerated: 1. equals()/hashCode() pair 2. toString() 3. componentN() functions 4. copy() function KOTLIN: COLLECTIONS #collections 

KOTLIN: COLLECTIONS val numbers: MutableList = mutableListOf(1, 2, 3) val readOnlyView: List = 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 

No dedicated syntax KOTLIN: COLLECTIONS #collections 

listOf(), mutableListOf(), setOf(), mutableSetOf() KOTLIN: COLLECTIONS #collections 

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 

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 

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