package com.coding.basic.week01;
import java.util.EmptyStackException;
public class Stack {
private ArrayList elementData = new ArrayList();
//入栈
public void push(Object o){
elementData.add(o);
}
//出栈
public Object pop(){
if(elementData.size() == 0) {
throw new EmptyStackException();
}
return elementData.remove(elementData.size() - 1);
}
//读取栈顶元素
public Object peek(){
if(elementData.size() == 0) {
throw new EmptyStackException();
}
return elementData.get(elementData.size() - 1);
}
public boolean isEmpty(){
return size() == 0;
}
public int size(){
return elementData.size();
}
}