Stack insertElementAt() method in Java with Example

The Java.util.Stack.insertElementAt(element, index) method is used to insert a particular element at the specified index of the Stack. Both the element and the position is passed as the parameters. If an element is inserted at a specified index, then all the elements are pushed upward by one and hence the capacity is increased, creating a space for the new element.
Syntax:

Stack.insertElementAt()

Parameters: The method accepts two parameters: 

• element: This is element required to be inserted into the Stack.
• index: This is of integer type and refers to the position where the new element is to be inserted.

Return Value: The method does not return anything.
Exception: The method throws ArrayIndexOutOfBoundsException if the index is an invalid number.
Below programs illustrate the Java.util.Stack.insertElementAt() method:
Program 1: Adding String elements into the Stack.

Java

// Java code to illustrate insertElementAt()
import java.util.*;

public class StackDemo {
    public static void main(String args[])
    {
        // Creating an empty Stack
        Stack<String> stack = new Stack<String>();

        // Use add() method to add elements into the Stack
        stack.add("Welcome");
        stack.add("To");
        stack.add("Geeks");
        stack.add("4");
        stack.add("Geeks");

        // Displaying the Stack
        System.out.println("Stack: " + stack);

        // Inserting element at 3rd position
        stack.insertElementAt("Hello", 2);

        // Inserting element at last position
        stack.insertElementAt("World", 6);

        // Displaying the final Stack
        System.out.println("The final Stack is "
                           + stack);
    }
}

Output:

Stack: [Welcome, To, Geeks, 4, Geeks]
The final Stack is [Welcome, To, Hello, Geeks, 4, Geeks, World]

Program 2: Adding Integer elements into the Stack. 

Java

// Java code to illustrate insertElementAt()
import java.util.*;

public class StackDemo {
    public static void main(String args[])
    {
        // Creating an empty Stack
        Stack<Integer> stack = new Stack<Integer>();

        // Use add() method to add elements into the Stack
        stack.add(10);
        stack.add(20);
        stack.add(30);
        stack.add(40);
        stack.add(50);

        // Displaying the Stack
        System.out.println("Stack: " + stack);

        // Inserting element at 1st position
        stack.insertElementAt(100, 0);

        // Inserting element at fifth position
        stack.insertElementAt(200, 4);

        // Displaying the final Stack
        System.out.println("The final Stack is "
                           + stack);
    }
}

Output:

Stack: [10, 20, 30, 40, 50]
The final Stack is [100, 10, 20, 30, 200, 40, 50]