LinkedListStack.java

import java.util.LinkedList;

public class LinkedListStack {

 private LinkedList<Integer> stack;

 public LinkedListStack(LinkedList<Integer> emptyStack){

 this.stack = emptyStack;
 }

 public boolean isEmpty() {
 return stack.size() == 0;
 }

 public int push(int n) {
 stack.add(n);
 return n;
 }

 public int pop() {
 return (isEmpty())? -1 : stack.removeLast();
 }

 public int peek() {
 Integer lastElement = stack.peekLast();
 return (lastElement == null)? -1 : (int)lastElement;
 }

 
}