ArrayList.add(int, E) in Java

ArrayList.add(int, E): This method is available in java.util.ArrayList class of Java.

Syntax:

void java.util.ArrayList.add(int index, E element)

This method takes two arguments. This method inserts the specified element at the specified position in this list.

Parameters: Two parameters are required for this method.

index: index at which the specified element is to be inserted.

element: the element to be inserted.

Throws:

1. IndexOutOfBoundsException - if the index is out of range(index < 0 || index > size())

Approach 1: When no exceptions

Java

import java.util.ArrayList;

public class ArrayListAddAtIndex {
    public static void main(String[] args) {
        ArrayList<Integer> arr = new ArrayList<>();
        arr.add(1);
        arr.add(100);
        arr.add(234);
        arr.add(0, 2);

        arr.forEach((n -> System.out.print(n + " ")));

    }
}

Output:

2 1 100 234 

Approach 2: IndexOutOfBoundsException 

Java

import java.util.ArrayList;

public class ArrayListAddAtIndex {
    public static void main(String[] args) {
        ArrayList<Integer> arr = new ArrayList<>();
        arr.add(1);
        arr.add(100);
        arr.add(234);
        arr.add(4, 2);

        arr.forEach((n -> System.out.print(n + " ")));

    }
}

Output:

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 4, Size: 3
	at java.base/java.util.ArrayList.rangeCheckForAdd(ArrayList.java:756)
	at java.base/java.util.ArrayList.add(ArrayList.java:481)