package com.liam.learn.code2017;
public class Stack {
private ArrayList elementData = new ArrayList();
public void push(Object o){
elementData.add(o);
}
public Object pop(){
return elementData.remove(elementData.size()-1);
}
public Object peek(){
return elementData.get(elementData.size()-1);
}
public boolean isEmpty(){
return elementData.size()==0;
}
public int size(){
return elementData.size();
}
}