/******************************************************************************
 * This program demonstrates the Stack ADT
 * 
 * Copyright © 2021 Richard Lesh.  All rights reserved.
 *****************************************************************************/

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.pureprogrammer.Utils;

public class ADTStack {

	static class IntegerStack {
// Internal representation for the stack is a list
		private List<Integer> stack = new ArrayList<>();

		public IntegerStack() {
			stack = new ArrayList<>();
		}

		public int pop() throws RuntimeException {
			if (stack.size() == 0) {
				throw new RuntimeException("Can't pop on empty stack!");
			}
			return stack.remove(stack.size() - 1);
		}

		public void push(int value) {
			stack.add(value);
		}

		public int peek() throws RuntimeException {
			if (stack.size() == 0) {
				throw new RuntimeException("Can't peek on empty stack!");
			}
			return stack.get(stack.size() - 1);
		}
	}

	public static void main(String[] args) {
		IntegerStack stack = new IntegerStack();
		for (int x = 1; x <= 10; ++x) {
			stack.push(x);
		}
		try {
			System.out.println(stack.peek());
			for (int x = 1; x <= 11; ++x) {
				System.out.println(stack.pop());
			}
		} catch (RuntimeException ex) {
			System.out.println(Utils.exceptionMessage(ex));
		} catch (Exception ex) {
			System.out.println("Unknown Exception!");
		}
	}
}