Stack.java

package basicstruct;

public class Stack {
	
	private ArrayList elementData = new ArrayList();
	
	public void push(Object o){	
		elementData.add(o);
	}
	//删除栈顶的值
	public Object pop(){
		return elementData.remove(elementData.size()-1);
	}
	//获取栈顶的值
	public Object peek(){
		return 	elementData.get(elementData.size()-1);
	}
	public boolean isEmpty(){
		return elementData.size()==0;
	}
	public int size(){
		return elementData.size();
	}
}