ЯсноПонятно24

package io.hexlet;

import java.util.EmptyStackException;

public class Stack<T> {

    private Node<T> top;

    public T push(T item) {
        Node<T> newNode = new Node<>(item);
        newNode.next = top;
        top = newNode;
        return item;
    }

    public T pop() {
        if (isEmpty()) {
            throw new EmptyStackException();
        }
        T item = top.data;
        top = top.next;
        return item;
    }

    public T peek() {
        if (isEmpty()) {
            throw new EmptyStackException();
        }
        return top.data;
    }

    public boolean isEmpty() {
        return top == null;
    }

    private static class Node<T> {
        private T data;
        private Node<T> next;

        public Node(T data) {
            this.data = data;
        }
    }
}

package io.hexlet;

import java.util.EmptyStackException;

public class Main {

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

        System.out.println("Is stack empty? " + stack.isEmpty());

        stack.push(1);
        stack.push(2);
        stack.push(3);

        System.out.println("Is stack empty? " + stack.isEmpty());
        System.out.println("Top element: " + stack.peek());

        System.out.println("Popped element: " + stack.pop());
        System.out.println("Top element after pop: " + stack.peek());
        System.out.println("Popped element: " + stack.pop());
        System.out.println("Popped element: " + stack.pop());

        try {
            System.out.println("Trying to pop from empty stack");
            stack.pop();
        } catch (EmptyStackException e) {
            System.out.println("EmptyStackException caught");
        }
    }
}