java容器类4：Queue深入解读

public interface Queue<E> extends Collection<E> {
    boolean add(E var1);

    boolean offer(E var1);

    E remove();

    E poll();

    E element();

    E peek();
}

public abstract class AbstractQueue<E> extends AbstractCollection<E>
    implements Queue<E> {

    protected AbstractQueue() {
    }

    public boolean add(E e) {
        if (offer(e))
            return true;
        else
            throw new IllegalStateException("Queue full");
    }


    public E remove() {
        E x = poll();
        if (x != null)
            return x;
        else
            throw new NoSuchElementException();
    }

    public E element() {
        E x = peek();
        if (x != null)
            return x;
        else
            throw new NoSuchElementException();
    }

    public void clear() {
        while (poll() != null)
            ;
    }

    public boolean addAll(Collection<? extends E> c) {
        if (c == null)
            throw new NullPointerException();
        if (c == this)
            throw new IllegalArgumentException();
        boolean modified = false;
        for (E e : c)
            if (add(e))
                modified = true;
        return modified;
    }
}

public ArrayDeque() {
        elements = 

    }


public ArrayDeque(int numElements) {
        

    }

public ArrayDeque(Collection<? extends E> c) {
        allocateElements(c.size());
        addAll(c);
    }

 /**
     * The index of the element at the head of the deque (which is the
     * element that would be removed by remove() or pop()); or an
     * arbitrary number equal to tail if the deque is empty.
     */
    transient int head;

    /**
     * The index at which the next element would be added to the tail
     * of the deque (via addLast(E), add(E), or push(E)).
     */
    transient int tail;

public void addFirst(E e) {
        if (e == null)
            throw new NullPointerException();
        

        if (head == tail)
            

    }

addLast(E e) {
    

 (e == 

)
        

 NullPointerException();
    elements[tail] = e;
    

 ( (tail = (tail + 1) & (elements.length - 1)) == head)
        doubleCapacity();
}

private static final int DEFAULT_INITIAL_CAPACITY = 11;
PriorityQueue<Integer> maxHeap=new PriorityQueue<Integer>(DEFAULT_INITIAL_CAPACITY, new Comparator<Integer>() {
        @Override
        public int compare(Integer o1, Integer o2) {
            return o2-o1;
        }
    });