Stack.java

package org.coding.one;

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