Java Stack push() Method

The push(E item) method in Java, part of the java.util.Stack class, is used to push an item onto the top of the stack. This method is fundamental to the stack's LIFO (Last-In-First-Out) behavior.

Table of Contents

1. Introduction
2. push(E item) Method Syntax
3. Understanding push(E item)
4. Examples
   • Basic Usage
   • Using push(E item) in a Loop
5. Real-World Use Case
6. Conclusion

Introduction

The push(E item) method adds an item to the top of the stack. It is a key operation for stack-based structures, ensuring that elements are added in the correct order for LIFO behavior.

push(E item) Method Syntax

The syntax for the push(E item) method is as follows:

public E push(E item)

Parameters:

• item: The item to be pushed onto the stack.

Returns:

• The item argument.

Throws:

• No exceptions are thrown by this method.

Understanding push(E item)

The push(E item) method adds an item to the top of the stack and returns the item. It ensures that the stack grows as new elements are added. This method does not throw any exceptions.

Examples

Basic Usage

To demonstrate the basic usage of push(E item), we will create a Stack object and push some elements onto the stack.

Example

import java.util.Stack;

public class PushExample {
    public static void main(String[] args) {
        Stack<String> stack = new Stack<>();

        // Push elements onto the stack
        stack.push("apple");
        stack.push("banana");
        stack.push("cherry");

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

Output:

Stack: [apple, banana, cherry]

Using push(E item) in a Loop

This example shows how to use push(E item) in a loop to add multiple elements to the stack.

Example

import java.util.Stack;

public class PushInLoopExample {
    public static void main(String[] args) {
        Stack<Integer> stack = new Stack<>();

        // Push elements onto the stack using a loop
        for (int i = 1; i <= 5; i++) {
            stack.push(i);
        }

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

Output:

Stack: [1, 2, 3, 4, 5]

Real-World Use Case

Browser History Navigation

In real-world applications, the push(E item) method can be used for browser history navigation, where each new page visited is pushed onto the stack.

Example

import java.util.Stack;

public class BrowserHistory {
    public static void main(String[] args) {
        Stack<String> history = new Stack<>();

        // User visits pages
        history.push("Home");
        history.push("About");
        history.push("Contact");

        // Current stack state
        System.out.println("Browser history: " + history);

        // User presses back button
        System.out.println("Going back from: " + history.pop()); // Contact

        // Current stack state
        System.out.println("Browser history after back: " + history);
    }
}

Output:

Browser history: [Home, About, Contact]
Going back from: Contact
Browser history after back: [Home, About]

Conclusion

The Stack.push(E item) method is used to add an item to the top of the stack. This method is essential for maintaining the stack's LIFO behavior, making it crucial for many stack-based operations. By understanding and using this method, you can efficiently manage stack-based data structures in your Java applications.