Hands-On Object-Oriented Programming with Kotlin

Calling the Java collection in Kotlin

Create a method in Java that returns an arrayList of integers:

public static ArrayList<Integer> getIntList(){    ArrayList<Integer> integers = new ArrayList<>();    integers.add(1);integers.add(2);integers.add(3);    return integers;}

getIntList returns an array that contains three elements. Call this function in Kotlin to access the list and add more elements in it:

var list = CallJava.getIntList()//var list: ArrayList<Int> = CallJava.getIntList()list.add(4)for (element in list) {   println("Element $element")}

CallJava.getIntList() returns ArrayList, which can be assigned to a list type of variables. We explicitly declare the type of the list by using the ArrayList<Int> name:

var list: ArrayList<Int> = CallJava.getIntList() ...