/* * Written by Doug Lea with assistance from members of JCP JSR-166 * Expert Group and released to the public domain. Use, modify, and * redistribute this code in any way without acknowledgement. */ package java.util; /** * AbstractQueue provides default implementations of * {@link #add add}, {@link #remove remove}, and {@link #element element} * based on * {@link #offer offer}, {@link #poll poll}, and {@link #peek peek}, * respectively but that * throw exceptions instead of indicating failure via false or * null returns. *
The provided implementations all assume that the base implementation
* does not allow null elements.
* @since 1.5
* @author Doug Lea
*/
public abstract class AbstractQueue
* This implementation iterates over the specified collection, and adds
* each object returned by the iterator to this collection, in turn.
*
* @param c collection whose elements are to be added to this queue
* @return true if this collection changed as a result of the
* call.
* @throws NullPointerException if c is null
*
*/
boolean addAll(Collection extends E> c) {
return super.addAll(c);
}
/** @throws NoSuchElementException {@inheritDoc} */
public E remove() {
E x = poll();
if (x != null)
return x;
else
throw new NoSuchElementException();
}
/** @throws NoSuchElementException {@inheritDoc} */
public E element() {
E x = peek();
if (x != null)
return x;
else
throw new NoSuchElementException();
}
/**
* Removes all of the elements from this collection.
* The collection will be empty after this call returns.
* This implementation repeatedly invokes {@link #poll poll} until it
* returns null.
*/
public void clear() {
while (poll() != null)
;
}
// XXX Remove this redundant declaration, pending response from Neal Gafter.
public abstract Iterator