package com.coding.basic;
public class Stack {
private ArrayList elementData = new ArrayList();
public void push(Object o){
elementData.add(o);
}
public Object pop(){
if(isEmpty()){
throw new RuntimeException("已为空");
}
Object o = elementData.get(elementData.size()-1);
elementData.remove(elementData.size()-1);
return o;
}
public Object peek(){
Object o = elementData.get(elementData.size()-1);
return o;
}
public boolean isEmpty(){
int size = elementData.size();
if(size == 0){
return true;
}else{
return false;
}
}
public int size(){
return elementData.size();
}
@Override
public String toString() {
return elementData.toString();
}
}