Java Stack peek() example

In this guide, you will learn about the Stack peek() method in Java programming and how to use it with an example.

1. Stack peek() Method Overview

Definition:

The peek() method of the Java Stack class is used to look at the object at the top of the stack without removing it.

Syntax:

stack.peek();

Parameters:

None.

Key Points:

- The method returns the top item of the stack without removing it.

- If the stack is empty, it will throw an EmptyStackException.

- The size of the stack remains unchanged after the operation.

- It allows you to inspect the top item without affecting the state of the stack.

2. Stack peek() Method Example

import java.util.Stack;

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

        // Push elements onto the stack for demonstration
        names.push("Alice");
        names.push("Bob");
        names.push("Charlie");

        System.out.println("Initial Stack: " + names);

        // Peek at the top element without removing it
        String name = names.peek();
        System.out.println("Top name without removal: " + name);
        System.out.println("Stack after peek: " + names);
    }
}

Output:

Initial Stack: [Alice, Bob, Charlie]
Top name without removal: Charlie
Stack after peek: [Alice, Bob, Charlie]

Explanation:

In the given example, the Stack initially contains three names: Alice, Bob, and Charlie. 

The peek() method is used to inspect the top element (Charlie) without removing it from the Stack. As observed in the output, the state of the Stack remains unchanged after the peek operation.

Related Stack and Queue Class methods

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Java Queue poll() example
Java Queue peek() example
Java Stack push() example
Java Stack pop() example
Java Stack peek() example
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