Queue.java

public class Queue {
    private LinkedList elementData = new LinkedList();

    public void enQueue(Object o){
        elementData.addLast(o);
    }

    public Object deQueue(){
        return elementData.removeFirst();
    }

    public boolean isEmpty(){
        return size() == 0;
    }

    public int size(){
        return elementData.size();
    }
}