package com.coding.basic;
public class Stack {
private ArrayList elementData = new ArrayList();
public void push(Object o){
elementData.add(elementData.size(), o);
}
public Object pop(){
Object obj = elementData.remove(elementData.size()-1);
return obj;
}
public Object peek(){
Object obj = elementData.get(0);
return obj;
}
public boolean isEmpty(){
return elementData.size()==0;
}
public int size(){
return elementData.size();
}
}