/*
* ��ArrayList������ʵ��Stack
*/
package com.firsthomework;
import java.util.ArrayList;
import java.util.EmptyStackException;
@SuppressWarnings("all")
public class MyStack {
private ArrayList elements=new ArrayList();
public void push(Object o){
elements.add(o);
}
public Object peek(){
if(elements.size()==0){
throw new EmptyStackException();
}
return elements.get(elements.size()-1);
}
public Object pop(){
int len=elements.size();
if(len==0){
throw new EmptyStackException();
}
return elements.remove(len-1);
}
public boolean empty(){
if(elements.size()==0){
return true;
}
return false;
}
public int size(){
return elements.size();
}
public static void main(String[] args) {
// TODO Auto-generated method stub
MyStack ms=new MyStack();
ms.push("top1");
ms.push("top2");
ms.push("top3");
System.out.println(ms.peek());
ms.pop();
System.out.println(ms.peek());
System.out.println(ms.size());
}
}