Stack.java

package com.github.wdn.coding2017.basic;

/**
 * 使用list实现比较简单
 * 可以考虑使用其它结构
 */
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();
	}
}