queue 用法

public class LatestElementQueue<E> {

    public LatestElementQueue() {}

    private LinkedList<E> list = new LinkedList<E>();

    ReentrantLock         lock = new ReentrantLock();

    public void add(E o) {
        list.addFirst(o);
    }

    public void addAll(List<E> es) {
        for (E e : es) {
            list.add(e);
        }
    }

    public void addAndRemOld(E o) {
        lock.lock();
        try {
            list.remove(o);
            list.add(o);
        } finally {
            lock.unlock();
        }

    }

    public E poll() {
        return list.removeLast();
    }

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

    public synchronized List<E> getTemp() {
        List<E> es = new ArrayList<E>();
        for (E e : list) {
            es.add(e);
        }
        return es;
    }
}