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