Implementation

Java Implementation of Stack

Java provides a built-in class Stack in the java.util package. Here’s how to use it:

Using the Stack Class

import java.util.Stack;

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

        // Push elements onto the stack
        stack.push(10);
        stack.push(20);
        stack.push(30);
        stack.push(40);

        // Display the elements in the stack
        System.out.println("Stack: " + stack);

        // Pop an element from the stack
        int poppedElement = stack.pop();
        System.out.println("Popped Element: " + poppedElement);

        // Display the stack after pop
        System.out.println("Stack after Pop: " + stack);

        // Peek at the top element of the stack without removing it
        int topElement = stack.peek();
        System.out.println("Top Element: " + topElement);

        // Check if the stack is empty
        boolean isEmpty = stack.isEmpty();
        System.out.println("Is the Stack empty? " + isEmpty);
    }
}

Explanation:

Import the Stack Class:

import java.util.Stack;

Create a Stack:

Stack<Integer> stack = new Stack<>();

Here, we create a stack of integers.

Push Elements onto the Stack:

stack.push(10);
stack.push(20);
stack.push(30);
stack.push(40);

We use the push() method to add elements to the top of the stack.

Display the Stack:

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

This prints the current elements in the stack.

Pop an Element from the Stack:

int poppedElement = stack.pop();
System.out.println("Popped Element: " + poppedElement);

The pop() method removes and returns the top element of the stack.

Display the Stack after Pop:

System.out.println("Stack after Pop: " + stack);

This prints the stack after removing an element.

Peek at the Top Element:

int topElement = stack.peek();
System.out.println("Top Element: " + topElement);

The peek() method returns the top element without removing it from the stack.

Check if the Stack is Empty:

boolean isEmpty = stack.isEmpty();
System.out.println("Is the Stack empty? " + isEmpty);

The isEmpty() method checks if the stack is empty and returns a boolean value.

Conclusion

This example demonstrates the basic operations of a stack, including pushing elements, popping elements, peeking at the top element, and checking if the stack is empty. The Stack class in Java provides a convenient way to implement stacks and use their core functionalities in applications.