--- jsr166/src/main/java/util/AbstractQueue.java 2003/10/19 13:38:29 1.21 +++ jsr166/src/main/java/util/AbstractQueue.java 2014/12/02 05:48:28 1.39 @@ -1,7 +1,7 @@ /* * 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. + * Expert Group and released to the public domain, as explained at + * http://creativecommons.org/publicdomain/zero/1.0/ */ package java.util; @@ -9,25 +9,28 @@ package java.util; /** * This class provides skeletal implementations of some {@link Queue} * operations. The implementations in this class are appropriate when - * the base implementation does not allow null + * the base implementation does not allow {@code null} * elements. Methods {@link #add add}, {@link #remove remove}, and * {@link #element element} are based on {@link #offer offer}, {@link - * #poll poll}, and {@link #peek peek}, respectively but throw - * exceptions instead of indicating failure via false or - * null returns. + * #poll poll}, and {@link #peek peek}, respectively, but throw + * exceptions instead of indicating failure via {@code false} or + * {@code null} returns. * - *
A Queue implementation that extends this class must + *
A {@code Queue} implementation that extends this class must * minimally define a method {@link Queue#offer} which does not permit - * insertion of null elements, along with methods {@link - * Queue#peek}, {@link Queue#poll}, {@link Collection#size}, and a - * {@link Collection#iterator} supporting {@link - * Iterator#remove}. Typically, additional methods will be overridden - * as well. If these requirements cannot be met, consider instead - * subclassing {@link AbstractCollection}. + * insertion of {@code null} elements, along with methods {@link + * Queue#peek}, {@link Queue#poll}, {@link Collection#size}, and + * {@link Collection#iterator}. Typically, additional methods will be + * overridden as well. If these requirements cannot be met, consider + * instead subclassing {@link AbstractCollection}. + * + *
This class is a member of the
+ *
+ * Java Collections Framework.
*
* @since 1.5
* @author Doug Lea
- * @param This implementation returns {@code true} if {@code offer} succeeds,
+ * else throws an {@code IllegalStateException}.
+ *
+ * @param e the element to add
+ * @return {@code true} (as specified by {@link Collection#add})
+ * @throws IllegalStateException if the element cannot be added at this
+ * time due to capacity restrictions
+ * @throws ClassCastException if the class of the specified element
+ * prevents it from being added to this queue
+ * @throws NullPointerException if the specified element is null and
+ * this queue does not permit null elements
+ * @throws IllegalArgumentException if some property of this element
+ * prevents it from being added to this queue
*/
- public boolean add(E o) {
- if (offer(o))
+ public boolean add(E e) {
+ if (offer(e))
return true;
else
throw new IllegalStateException("Queue full");
}
/**
- * Retrieves and removes the head of this queue.
- * This implementation returns the result of poll
+ * Retrieves and removes the head of this queue. This method differs
+ * from {@link #poll poll} only in that it throws an exception if this
+ * queue is empty.
+ *
+ * This implementation returns the result of {@code poll}
* unless the queue is empty.
*
- * @return the head of this queue.
- * @throws NoSuchElementException if this queue is empty.
+ * @return the head of this queue
+ * @throws NoSuchElementException if this queue is empty
*/
public E remove() {
E x = poll();
@@ -75,14 +88,16 @@ public abstract class AbstractQueue This implementation returns the result of {@code peek}
* unless the queue is empty.
*
- * @return the head of this queue.
- * @throws NoSuchElementException if this queue is empty.
+ * @return the head of this queue
+ * @throws NoSuchElementException if this queue is empty
*/
public E element() {
E x = peek();
@@ -93,10 +108,11 @@ public abstract class AbstractQueue This implementation repeatedly invokes {@link #poll poll} until it
- * returns null.
+ * returns {@code null}.
*/
public void clear() {
while (poll() != null)
@@ -106,25 +122,30 @@ public abstract class AbstractQueue This implementation iterates over the specified collection,
* and adds each element returned by the iterator to this
- * collection, in turn. A runtime exception encountered while
+ * queue, in turn. A runtime exception encountered while
* trying to add an element (including, in particular, a
- * null element) may result in only some of the elements
+ * {@code null} element) may result in only some of the elements
* having been successfully added when the associated exception is
* thrown.
*
- * @param c collection whose elements are to be added to this collection.
- * @return true if this collection changed as a result of the
- * call.
- * @throws NullPointerException if the specified collection, or
- * any of its elements are null.
- * @throws IllegalArgumentException if c is this queue.
- *
+ * @param c collection containing elements to be added to this queue
+ * @return {@code true} if this queue changed as a result of the call
+ * @throws ClassCastException if the class of an element of the specified
+ * collection prevents it from being added to this queue
+ * @throws NullPointerException if the specified collection contains a
+ * null element and this queue does not permit null elements,
+ * or if the specified collection is null
+ * @throws IllegalArgumentException if some property of an element of the
+ * specified collection prevents it from being added to this
+ * queue, or if the specified collection is this queue
+ * @throws IllegalStateException if not all the elements can be added at
+ * this time due to insertion restrictions
* @see #add(Object)
*/
public boolean addAll(Collection extends E> c) {
@@ -132,13 +153,11 @@ public abstract class AbstractQueue