FIFO Queue

package dataStructures;

public interface Queue {
    public void enqueue(Object value);
    public Object dequeue() throws EmptyQueueException;
    public void clear();
    public int size();
    public boolean isEmpty();
}

package dataStructures;

public class ListFifoQueue implements Queue {
    private final List _list;

    public ListFifoQueue(List list) {
        assert list != null : "list can’t be null";
        _list = list;
    }

    public ListFifoQueue() {
        this(new LinkedList());
    }

    public void enqueue(Object value) {
        _list.add(value);
    }

    public Object dequeue() throws EmptyQueueException {
        if (isEmpty()) {
            throw new EmptyQueueException();
        }
        return _list.delete(0);
    }

    public void clear() {
        _list.clear();
    }

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

    public boolean isEmpty() {
        return _list.isEmpty();
    }
}