ArrayList

Question

I am getting the output as 1,3,4 for the below program instead of 2,3,4.

Can someone please explain why it is being considered as the reference but not the value in Integer case ?

import java.util.ArrayList;

public class MyClass {
public static void main(String[ ] args) {
ArrayList<Integer> colors = new ArrayList<Integer>();
colors.add(1);
colors.add(2);
colors.add(3);
colors.add(4);
colors.remove(1);

System.out.println(colors);
}
}

Answer 1

import java.util.ArrayList;

public class MyClass {
public static void main(String[ ] args) {
ArrayList<Integer> colors = new ArrayList<Integer>();
colors.add(1); // index 0
colors.add(2);
// index 1
colors.add(3);
// index 2
colors.add(4);
// index 3
colors.remove(1);
// remove index no 1 (it mens 2)

System.out.println(colors);
}
}

Answer 2

The reason 1 isn't being deleted from the arraylist is because the .remove function will remove any element at a specific index, and because you're deleting the element at index 1, 2 gets deleted

Answer 3

When U put the int value into 'remove' method it will always refer to Index. U can avoid that by cast value into Integer. Exmpl: colors.remove((Integer) 1)