package com.github.lqingchenl.coding2017.basic;
public class Stack {
private ArrayList elementData = new ArrayList();
private int size = 0;
public void push(Object o) {
elementData.add(o);
size++;
}
public Object pop() {
Object o = elementData.get(size - 1);
elementData.remove(size - 1);
size--;
return o;
}
public Object peek() {
return elementData.get(size - 1);
}
public boolean isEmpty() {
if (elementData.size() == 0)
return true;
return false;
}
public int size() {
return size;
}
}