Comprehensive Overview of the Java Stack Data Structure

Java Stack Overview

Introduction to Stack

A Stack is a data structure that follows the Last In, First Out (LIFO) principle, meaning that the last element added to the stack is the first one to be removed.

Key Concepts

  • Push: Adding an element to the top of the stack.
  • Pop: Removing the top element from the stack.
  • Peek: Viewing the top element without removing it.
  • Empty: Checking if the stack has no elements.

Java Stack Class

The Stack class in Java is part of the java.util package. It extends the Vector class, which means it inherits methods from Vector.

Basic Operations

Checking if Stack is Empty

boolean isEmpty = stack.isEmpty(); // Returns false

Peeking the Top Element

int top = stack.peek(); // Returns 20 without removing it

Popping Elements

int topElement = stack.pop(); // Removes 30

Pushing Elements

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

Creating a Stack

Stack<Integer> stack = new Stack<>;

Example Usage

import java.util.Stack;

public class StackExample {
    public static void main(String[] args) {
        Stack<String> stack = new Stack<>;
        stack.push("Apple");
        stack.push("Banana");
        stack.push("Cherry");

        System.out.println("Top element: " + stack.peek()); // Cherry
        System.out.println("Popped element: " + stack.pop()); // Cherry
        System.out.println("Is stack empty? " + stack.isEmpty()); // false
    }
}

Conclusion

The Stack class provides a simple yet effective way to manage data with LIFO behavior in Java. It is useful in various applications such as expression evaluation, backtracking algorithms, and undo mechanisms in software.