Question

public class Test {
    public static void main(String[] args) {
        int[] arr = new int[5];
        arr[0]    = 1;
        method(arr);
        System.out.println(arr[0]);
    }

    private static void method(int[] array)
    {
        array[0] = 2;
    }
}

After invoking method, arr[0] becomes 2. Why is that!?

Answer 1

You can call set methods on objects passed to a method. Java is pass by value, which means that you can’t replace an object in a method, though you can call set methods on an object.

If Java were pass by reference, this would pass:

public class Test {

public static void main(String[] args) {
    Test test = new Test();
    int j = 0;
    test.setToOne(j);
    assert j == 1;
}

public void setToOne(int i) {
    i = 1;
}
}