Stack push() Method in Java

Java.util.Stack.push(E element) method is used to push an element into the Stack. The element gets pushed onto the top of the Stack.

Syntax:

STACK.push(E element)

Parameters: The method accepts one parameter element of type Stack and refers to the element to be pushed into the stack.

Return Value: The method returns the argument passed.  It also accepts the null value unlike ArrayDeque.push() which throws java.lang.NullPointerException on doing the same.

Below programs illustrate the Java.util.Stack.push() method: 

Program 1: Adding String elements into the Stack. 

Java

// Java Code to illustrate push() Method

import java.util.*;

// Main class
public class StackDemo {

    // Main driver method
    public static void main(String args[])
    {
        // Creating an empty Stack
        Stack& lt;
        String& gt;
        STACK = new Stack& lt;
        String& gt;
        ();

        // Adding elements into the stack
        // using push() method
        STACK.push(" Welcome & quot;);
        STACK.push(" To & quot;);
        STACK.push(" Geeks & quot;);
        STACK.push(" For & quot;);
        STACK.push(" Geeks & quot;);

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

        // Pushing elements into the stack
        STACK.push(" Hello & quot;);
        STACK.push(" World & quot;);

        // Displaying the final Stack
        System.out.println(" Final Stack
                           : "
                           + STACK);
    }
}

Output:

Initial Stack: [Welcome, To, Geeks, For, Geeks]
Final Stack: [Welcome, To, Geeks, For, Geeks, Hello, World]

Program 2: Adding Integer elements into the Stack. 

Java

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

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

        // Use push() to add elements into the Stack
        STACK.push(10);
        STACK.push(15);
        STACK.push(30);
        STACK.push(20);
        STACK.push(5);
        STACK.push(null);

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

        // Pushing elements into the Stack
        STACK.push(1254);
        STACK.push(4521);

        // Displaying the final Stack
        System.out.println("Final Stack: " + STACK);
    }
}

Output:

Initial Stack: [10, 15, 30, 20, 5]
Final Stack: [10, 15, 30, 20, 5, 1254, 4521]