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