package com.danny.hw1;
public class Stack {
private ArrayList elementData = new ArrayList();
public void push(Object o){
this.elementData.add(o);
}
public Object pop(){
int size = this.elementData.size();
if ( size > 0 ) {
return this.elementData.remove(size - 1 );
} else{
throw new IndexOutOfBoundsException("Stack is empty");
}
}
public Object peek(){
if ( size() > 0 ) {
return this.elementData.get(size() - 1 );
} else{
throw new IndexOutOfBoundsException("Stack is empty");
}
}
public boolean isEmpty(){
return size() == 0;
}
public int size(){
return this.elementData.size();
}
public Stack() {
// TODO Auto-generated constructor stub
}
}