package com.leaning.code;
public class Stack {
private ArrayList list = new ArrayList();
private int size;
public void push(Object o){
list.add(o);
size ++;
}
public Object pop(){
return list.get(--size);
}
public Object peek(){
return list.get(size-1);
}
public boolean isEmpty(){
return size == 0;
}
public int size(){
return size;
}
}