RFR doclint issues in j.u.Deque & Queue

Mike Duigou mike.duigou at oracle.com
Thu Aug 1 17:35:28 UTC 2013


Looks good to me. Thanks for incorporating the 6546713 changes.

Can we also incorporate the changes in JDK-7178639:

http://cr.openjdk.java.net/~mduigou/JDK-7178639/0/webrev/

into this changeset? It seems like an an opportune time.

Mike

On Aug 1 2013, at 03:34 , Chris Hegarty wrote:

> These changes are already committed in the jsr166 CVS, this is a request to pull them into jdk8.
> 
> Specdiff has been run, and there is nothing surprising.
> The doclint issues are specifically around the addition of a caption to the tables, the remaining changes are cleanup, <code> -> {@code ..}, etc.
> 
> Note: there are some minor doc updates around throwing an IllegalStateException if no space is currently available in Deque, which is already part of the spec.
> 
> Martin, Doug,
> The 166 CVS is trivially missing 6546713,
> http://cr.openjdk.java.net/~mduigou/6546713/0/webrev/src/share/classes/java/util/Deque.java.sdiff.html. Once the changes below are in jdk8, you can easily sync with the 8 version, or apply the diffs from the webrev link above.
> 
> I have already reviewed these changes, but more reviewers are welcome.
> 
> 
> diff -r 4bd51f6268f4 src/share/classes/java/util/Deque.java
> --- a/src/share/classes/java/util/Deque.java	Wed Jul 24 10:57:02 2013 +0200
> +++ b/src/share/classes/java/util/Deque.java	Thu Aug 01 11:24:48 2013 +0100
> @@ -38,7 +38,7 @@ package java.util;
> /**
>  * A linear collection that supports element insertion and removal at
>  * both ends.  The name <i>deque</i> is short for "double ended queue"
> - * and is usually pronounced "deck".  Most <tt>Deque</tt>
> + * and is usually pronounced "deck".  Most {@code Deque}
>  * implementations place no fixed limits on the number of elements
>  * they may contain, but this interface supports capacity-restricted
>  * deques as well as those with no fixed size limit.
> @@ -47,10 +47,10 @@ package java.util;
>  * ends of the deque.  Methods are provided to insert, remove, and
>  * examine the element.  Each of these methods exists in two forms:
>  * one throws an exception if the operation fails, the other returns a
> - * special value (either <tt>null</tt> or <tt>false</tt>, depending on
> + * special value (either {@code null} or {@code false}, depending on
>  * the operation).  The latter form of the insert operation is
>  * designed specifically for use with capacity-restricted
> - * <tt>Deque</tt> implementations; in most implementations, insert
> + * {@code Deque} implementations; in most implementations, insert
>  * operations cannot fail.
>  *
>  * <p>The twelve methods described above are summarized in the
> @@ -58,6 +58,7 @@ package java.util;
>  *
>  * <p>
>  * <table BORDER CELLPADDING=3 CELLSPACING=1>
> + * <caption>Summary of Deque methods</caption>
>  *  <tr>
>  *    <td></td>
>  *    <td ALIGN=CENTER COLSPAN = 2> <b>First Element (Head)</b></td>
> @@ -72,38 +73,39 @@ package java.util;
>  *  </tr>
>  *  <tr>
>  *    <td><b>Insert</b></td>
> - *    <td>{@link #addFirst addFirst(e)}</td>
> - *    <td>{@link #offerFirst offerFirst(e)}</td>
> - *    <td>{@link #addLast addLast(e)}</td>
> - *    <td>{@link #offerLast offerLast(e)}</td>
> + *    <td>{@link Deque#addFirst addFirst(e)}</td>
> + *    <td>{@link Deque#offerFirst offerFirst(e)}</td>
> + *    <td>{@link Deque#addLast addLast(e)}</td>
> + *    <td>{@link Deque#offerLast offerLast(e)}</td>
>  *  </tr>
>  *  <tr>
>  *    <td><b>Remove</b></td>
> - *    <td>{@link #removeFirst removeFirst()}</td>
> - *    <td>{@link #pollFirst pollFirst()}</td>
> - *    <td>{@link #removeLast removeLast()}</td>
> - *    <td>{@link #pollLast pollLast()}</td>
> + *    <td>{@link Deque#removeFirst removeFirst()}</td>
> + *    <td>{@link Deque#pollFirst pollFirst()}</td>
> + *    <td>{@link Deque#removeLast removeLast()}</td>
> + *    <td>{@link Deque#pollLast pollLast()}</td>
>  *  </tr>
>  *  <tr>
>  *    <td><b>Examine</b></td>
> - *    <td>{@link #getFirst getFirst()}</td>
> - *    <td>{@link #peekFirst peekFirst()}</td>
> - *    <td>{@link #getLast getLast()}</td>
> - *    <td>{@link #peekLast peekLast()}</td>
> + *    <td>{@link Deque#getFirst getFirst()}</td>
> + *    <td>{@link Deque#peekFirst peekFirst()}</td>
> + *    <td>{@link Deque#getLast getLast()}</td>
> + *    <td>{@link Deque#peekLast peekLast()}</td>
>  *  </tr>
>  * </table>
>  *
>  * <p>This interface extends the {@link Queue} interface.  When a deque is
>  * used as a queue, FIFO (First-In-First-Out) behavior results. Elements are
>  * added at the end of the deque and removed from the beginning.  The methods
> - * inherited from the <tt>Queue</tt> interface are precisely equivalent to
> - * <tt>Deque</tt> methods as indicated in the following table:
> + * inherited from the {@code Queue} interface are precisely equivalent to
> + * {@code Deque} methods as indicated in the following table:
>  *
>  * <p>
>  * <table BORDER CELLPADDING=3 CELLSPACING=1>
> + * <caption>Comparison of Queue and Deque methods</caption>
>  *  <tr>
> - *    <td ALIGN=CENTER> <b><tt>Queue</tt> Method</b></td>
> - *    <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td>
> + *    <td ALIGN=CENTER> <b>{@code Queue} Method</b></td>
> + *    <td ALIGN=CENTER> <b>Equivalent {@code Deque} Method</b></td>
>  *  </tr>
>  *  <tr>
>  *    <td>{@link java.util.Queue#add add(e)}</td>
> @@ -135,13 +137,14 @@ package java.util;
>  * interface should be used in preference to the legacy {@link Stack} class.
>  * When a deque is used as a stack, elements are pushed and popped from the
>  * beginning of the deque.  Stack methods are precisely equivalent to
> - * <tt>Deque</tt> methods as indicated in the table below:
> + * {@code Deque} methods as indicated in the table below:
>  *
>  * <p>
>  * <table BORDER CELLPADDING=3 CELLSPACING=1>
> + * <caption>Comparison of Stack and Deque methods</caption>
>  *  <tr>
>  *    <td ALIGN=CENTER> <b>Stack Method</b></td>
> - *    <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td>
> + *    <td ALIGN=CENTER> <b>Equivalent {@code Deque} Method</b></td>
>  *  </tr>
>  *  <tr>
>  *    <td>{@link #push push(e)}</td>
> @@ -168,18 +171,18 @@ package java.util;
>  * <p>Unlike the {@link List} interface, this interface does not
>  * provide support for indexed access to elements.
>  *
> - * <p>While <tt>Deque</tt> implementations are not strictly required
> + * <p>While {@code Deque} implementations are not strictly required
>  * to prohibit the insertion of null elements, they are strongly
> - * encouraged to do so.  Users of any <tt>Deque</tt> implementations
> + * encouraged to do so.  Users of any {@code Deque} implementations
>  * that do allow null elements are strongly encouraged <i>not</i> to
>  * take advantage of the ability to insert nulls.  This is so because
> - * <tt>null</tt> is used as a special return value by various methods
> + * {@code null} is used as a special return value by various methods
>  * to indicated that the deque is empty.
>  *
> - * <p><tt>Deque</tt> implementations generally do not define
> - * element-based versions of the <tt>equals</tt> and <tt>hashCode</tt>
> + * <p>{@code Deque} implementations generally do not define
> + * element-based versions of the {@code equals} and {@code hashCode}
>  * methods, but instead inherit the identity-based versions from class
> - * <tt>Object</tt>.
> + * {@code Object}.
>  *
>  * <p>This interface is a member of the <a
>  * href="{@docRoot}/../technotes/guides/collections/index.html"> Java Collections
> @@ -190,13 +193,13 @@ package java.util;
>  * @since  1.6
>  * @param <E> the type of elements held in this collection
>  */
> -
> public interface Deque<E> extends Queue<E> {
>     /**
>      * Inserts the specified element at the front of this deque if it is
> -     * possible to do so immediately without violating capacity restrictions.
> -     * When using a capacity-restricted deque, it is generally preferable to
> -     * use method {@link #offerFirst}.
> +     * possible to do so immediately without violating capacity restrictions,
> +     * throwing an {@code IllegalStateException} if no space is currently
> +     * available.  When using a capacity-restricted deque, it is generally
> +     * preferable to use method {@link #offerFirst}.
>      *
>      * @param e the element to add
>      * @throws IllegalStateException if the element cannot be added at this
> @@ -212,9 +215,10 @@ public interface Deque<E> extends Queue<
> 
>     /**
>      * Inserts the specified element at the end of this deque if it is
> -     * possible to do so immediately without violating capacity restrictions.
> -     * When using a capacity-restricted deque, it is generally preferable to
> -     * use method {@link #offerLast}.
> +     * possible to do so immediately without violating capacity restrictions,
> +     * throwing an {@code IllegalStateException} if no space is currently
> +     * available.  When using a capacity-restricted deque, it is generally
> +     * preferable to use method {@link #offerLast}.
>      *
>      * <p>This method is equivalent to {@link #add}.
>      *
> @@ -237,8 +241,8 @@ public interface Deque<E> extends Queue<
>      * which can fail to insert an element only by throwing an exception.
>      *
>      * @param e the element to add
> -     * @return <tt>true</tt> if the element was added to this deque, else
> -     *         <tt>false</tt>
> +     * @return {@code true} if the element was added to this deque, else
> +     *         {@code false}
>      * @throws ClassCastException if the class of the specified element
>      *         prevents it from being added to this deque
>      * @throws NullPointerException if the specified element is null and this
> @@ -255,8 +259,8 @@ public interface Deque<E> extends Queue<
>      * which can fail to insert an element only by throwing an exception.
>      *
>      * @param e the element to add
> -     * @return <tt>true</tt> if the element was added to this deque, else
> -     *         <tt>false</tt>
> +     * @return {@code true} if the element was added to this deque, else
> +     *         {@code false}
>      * @throws ClassCastException if the class of the specified element
>      *         prevents it from being added to this deque
>      * @throws NullPointerException if the specified element is null and this
> @@ -288,17 +292,17 @@ public interface Deque<E> extends Queue<
> 
>     /**
>      * Retrieves and removes the first element of this deque,
> -     * or returns <tt>null</tt> if this deque is empty.
> +     * or returns {@code null} if this deque is empty.
>      *
> -     * @return the head of this deque, or <tt>null</tt> if this deque is empty
> +     * @return the head of this deque, or {@code null} if this deque is empty
>      */
>     E pollFirst();
> 
>     /**
>      * Retrieves and removes the last element of this deque,
> -     * or returns <tt>null</tt> if this deque is empty.
> +     * or returns {@code null} if this deque is empty.
>      *
> -     * @return the tail of this deque, or <tt>null</tt> if this deque is empty
> +     * @return the tail of this deque, or {@code null} if this deque is empty
>      */
>     E pollLast();
> 
> @@ -325,31 +329,31 @@ public interface Deque<E> extends Queue<
> 
>     /**
>      * Retrieves, but does not remove, the first element of this deque,
> -     * or returns <tt>null</tt> if this deque is empty.
> +     * or returns {@code null} if this deque is empty.
>      *
> -     * @return the head of this deque, or <tt>null</tt> if this deque is empty
> +     * @return the head of this deque, or {@code null} if this deque is empty
>      */
>     E peekFirst();
> 
>     /**
>      * Retrieves, but does not remove, the last element of this deque,
> -     * or returns <tt>null</tt> if this deque is empty.
> +     * or returns {@code null} if this deque is empty.
>      *
> -     * @return the tail of this deque, or <tt>null</tt> if this deque is empty
> +     * @return the tail of this deque, or {@code null} if this deque is empty
>      */
>     E peekLast();
> 
>     /**
>      * Removes the first occurrence of the specified element from this deque.
>      * If the deque does not contain the element, it is unchanged.
> -     * More formally, removes the first element <tt>e</tt> such that
> +     * More formally, removes the first element {@code e} such that
>      * <tt>(o==null ? e==null : o.equals(e))</tt>
>      * (if such an element exists).
> -     * Returns <tt>true</tt> if this deque contained the specified element
> +     * Returns {@code true} if this deque contained the specified element
>      * (or equivalently, if this deque changed as a result of the call).
>      *
>      * @param o element to be removed from this deque, if present
> -     * @return <tt>true</tt> if an element was removed as a result of this call
> +     * @return {@code true} if an element was removed as a result of this call
>      * @throws ClassCastException if the class of the specified element
>      *         is incompatible with this deque
>      * (<a href="Collection.html#optional-restrictions">optional</a>)
> @@ -362,14 +366,14 @@ public interface Deque<E> extends Queue<
>     /**
>      * Removes the last occurrence of the specified element from this deque.
>      * If the deque does not contain the element, it is unchanged.
> -     * More formally, removes the last element <tt>e</tt> such that
> +     * More formally, removes the last element {@code e} such that
>      * <tt>(o==null ? e==null : o.equals(e))</tt>
>      * (if such an element exists).
> -     * Returns <tt>true</tt> if this deque contained the specified element
> +     * Returns {@code true} if this deque contained the specified element
>      * (or equivalently, if this deque changed as a result of the call).
>      *
>      * @param o element to be removed from this deque, if present
> -     * @return <tt>true</tt> if an element was removed as a result of this call
> +     * @return {@code true} if an element was removed as a result of this call
>      * @throws ClassCastException if the class of the specified element
>      *         is incompatible with this deque
>      * (<a href="Collection.html#optional-restrictions">optional</a>)
> @@ -385,15 +389,15 @@ public interface Deque<E> extends Queue<
>      * Inserts the specified element into the queue represented by this deque
>      * (in other words, at the tail of this deque) if it is possible to do so
>      * immediately without violating capacity restrictions, returning
> -     * <tt>true</tt> upon success and throwing an
> -     * <tt>IllegalStateException</tt> if no space is currently available.
> +     * {@code true} upon success and throwing an
> +     * {@code IllegalStateException} if no space is currently available.
>      * When using a capacity-restricted deque, it is generally preferable to
>      * use {@link #offer(Object) offer}.
>      *
>      * <p>This method is equivalent to {@link #addLast}.
>      *
>      * @param e the element to add
> -     * @return <tt>true</tt> (as specified by {@link Collection#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
> @@ -409,7 +413,7 @@ public interface Deque<E> extends Queue<
>      * Inserts the specified element into the queue represented by this deque
>      * (in other words, at the tail of this deque) if it is possible to do so
>      * immediately without violating capacity restrictions, returning
> -     * <tt>true</tt> upon success and <tt>false</tt> if no space is currently
> +     * {@code true} upon success and {@code false} if no space is currently
>      * available.  When using a capacity-restricted deque, this method is
>      * generally preferable to the {@link #add} method, which can fail to
>      * insert an element only by throwing an exception.
> @@ -417,8 +421,8 @@ public interface Deque<E> extends Queue<
>      * <p>This method is equivalent to {@link #offerLast}.
>      *
>      * @param e the element to add
> -     * @return <tt>true</tt> if the element was added to this deque, else
> -     *         <tt>false</tt>
> +     * @return {@code true} if the element was added to this deque, else
> +     *         {@code false}
>      * @throws ClassCastException if the class of the specified element
>      *         prevents it from being added to this deque
>      * @throws NullPointerException if the specified element is null and this
> @@ -444,11 +448,11 @@ public interface Deque<E> extends Queue<
>     /**
>      * Retrieves and removes the head of the queue represented by this deque
>      * (in other words, the first element of this deque), or returns
> -     * <tt>null</tt> if this deque is empty.
> +     * {@code null} if this deque is empty.
>      *
>      * <p>This method is equivalent to {@link #pollFirst()}.
>      *
> -     * @return the first element of this deque, or <tt>null</tt> if
> +     * @return the first element of this deque, or {@code null} if
>      *         this deque is empty
>      */
>     E poll();
> @@ -469,12 +473,12 @@ public interface Deque<E> extends Queue<
>     /**
>      * Retrieves, but does not remove, the head of the queue represented by
>      * this deque (in other words, the first element of this deque), or
> -     * returns <tt>null</tt> if this deque is empty.
> +     * returns {@code null} if this deque is empty.
>      *
>      * <p>This method is equivalent to {@link #peekFirst()}.
>      *
>      * @return the head of the queue represented by this deque, or
> -     *         <tt>null</tt> if this deque is empty
> +     *         {@code null} if this deque is empty
>      */
>     E peek();
> 
> @@ -484,9 +488,8 @@ public interface Deque<E> extends Queue<
>     /**
>      * Pushes an element onto the stack represented by this deque (in other
>      * words, at the head of this deque) if it is possible to do so
> -     * immediately without violating capacity restrictions, returning
> -     * <tt>true</tt> upon success and throwing an
> -     * <tt>IllegalStateException</tt> if no space is currently available.
> +     * immediately without violating capacity restrictions, throwing an
> +     * {@code IllegalStateException} if no space is currently available.
>      *
>      * <p>This method is equivalent to {@link #addFirst}.
>      *
> @@ -520,16 +523,16 @@ public interface Deque<E> extends Queue<
>     /**
>      * Removes the first occurrence of the specified element from this deque.
>      * If the deque does not contain the element, it is unchanged.
> -     * More formally, removes the first element <tt>e</tt> such that
> +     * More formally, removes the first element {@code e} such that
>      * <tt>(o==null ? e==null : o.equals(e))</tt>
>      * (if such an element exists).
> -     * Returns <tt>true</tt> if this deque contained the specified element
> +     * Returns {@code true} if this deque contained the specified element
>      * (or equivalently, if this deque changed as a result of the call).
>      *
> -     * <p>This method is equivalent to {@link #removeFirstOccurrence}.
> +     * <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}.
>      *
>      * @param o element to be removed from this deque, if present
> -     * @return <tt>true</tt> if an element was removed as a result of this call
> +     * @return {@code true} if an element was removed as a result of this call
>      * @throws ClassCastException if the class of the specified element
>      *         is incompatible with this deque
>      * (<a href="Collection.html#optional-restrictions">optional</a>)
> @@ -540,13 +543,13 @@ public interface Deque<E> extends Queue<
>     boolean remove(Object o);
> 
>     /**
> -     * Returns <tt>true</tt> if this deque contains the specified element.
> -     * More formally, returns <tt>true</tt> if and only if this deque contains
> -     * at least one element <tt>e</tt> such that
> +     * Returns {@code true} if this deque contains the specified element.
> +     * More formally, returns {@code true} if and only if this deque contains
> +     * at least one element {@code e} such that
>      * <tt>(o==null ? e==null : o.equals(e))</tt>.
>      *
>      * @param o element whose presence in this deque is to be tested
> -     * @return <tt>true</tt> if this deque contains the specified element
> +     * @return {@code true} if this deque contains the specified element
>      * @throws ClassCastException if the type of the specified element
>      *         is incompatible with this deque
>      * (<a href="Collection.html#optional-restrictions">optional</a>)
> diff -r 4bd51f6268f4 src/share/classes/java/util/Queue.java
> --- a/src/share/classes/java/util/Queue.java	Wed Jul 24 10:57:02 2013 +0200
> +++ b/src/share/classes/java/util/Queue.java	Thu Aug 01 11:24:48 2013 +0100
> @@ -41,14 +41,15 @@ package java.util;
>  * queues provide additional insertion, extraction, and inspection
>  * operations.  Each of these methods exists in two forms: one throws
>  * an exception if the operation fails, the other returns a special
> - * value (either <tt>null</tt> or <tt>false</tt>, depending on the
> + * value (either {@code null} or {@code false}, depending on the
>  * operation).  The latter form of the insert operation is designed
> - * specifically for use with capacity-restricted <tt>Queue</tt>
> + * specifically for use with capacity-restricted {@code Queue}
>  * implementations; in most implementations, insert operations cannot
>  * fail.
>  *
>  * <p>
>  * <table BORDER CELLPADDING=3 CELLSPACING=1>
> + * <caption>Summary of Queue methods</caption>
>  *  <tr>
>  *    <td></td>
>  *    <td ALIGN=CENTER><em>Throws exception</em></td>
> @@ -56,18 +57,18 @@ package java.util;
>  *  </tr>
>  *  <tr>
>  *    <td><b>Insert</b></td>
> - *    <td>{@link #add add(e)}</td>
> - *    <td>{@link #offer offer(e)}</td>
> + *    <td>{@link Queue#add add(e)}</td>
> + *    <td>{@link Queue#offer offer(e)}</td>
>  *  </tr>
>  *  <tr>
>  *    <td><b>Remove</b></td>
> - *    <td>{@link #remove remove()}</td>
> - *    <td>{@link #poll poll()}</td>
> + *    <td>{@link Queue#remove remove()}</td>
> + *    <td>{@link Queue#poll poll()}</td>
>  *  </tr>
>  *  <tr>
>  *    <td><b>Examine</b></td>
> - *    <td>{@link #element element()}</td>
> - *    <td>{@link #peek peek()}</td>
> + *    <td>{@link Queue#element element()}</td>
> + *    <td>{@link Queue#peek peek()}</td>
>  *  </tr>
>  * </table>
>  *
> @@ -79,15 +80,15 @@ package java.util;
>  * Whatever the ordering used, the <em>head</em> of the queue is that
>  * element which would be removed by a call to {@link #remove() } or
>  * {@link #poll()}.  In a FIFO queue, all new elements are inserted at
> - * the <em> tail</em> of the queue. Other kinds of queues may use
> - * different placement rules.  Every <tt>Queue</tt> implementation
> + * the <em>tail</em> of the queue. Other kinds of queues may use
> + * different placement rules.  Every {@code Queue} implementation
>  * must specify its ordering properties.
>  *
>  * <p>The {@link #offer offer} method inserts an element if possible,
> - * otherwise returning <tt>false</tt>.  This differs from the {@link
> + * otherwise returning {@code false}.  This differs from the {@link
>  * java.util.Collection#add Collection.add} method, which can fail to
>  * add an element only by throwing an unchecked exception.  The
> - * <tt>offer</tt> method is designed for use when failure is a normal,
> + * {@code offer} method is designed for use when failure is a normal,
>  * rather than exceptional occurrence, for example, in fixed-capacity
>  * (or "bounded") queues.
>  *
> @@ -95,32 +96,32 @@ package java.util;
>  * return the head of the queue.
>  * Exactly which element is removed from the queue is a
>  * function of the queue's ordering policy, which differs from
> - * implementation to implementation. The <tt>remove()</tt> and
> - * <tt>poll()</tt> methods differ only in their behavior when the
> - * queue is empty: the <tt>remove()</tt> method throws an exception,
> - * while the <tt>poll()</tt> method returns <tt>null</tt>.
> + * implementation to implementation. The {@code remove()} and
> + * {@code poll()} methods differ only in their behavior when the
> + * queue is empty: the {@code remove()} method throws an exception,
> + * while the {@code poll()} method returns {@code null}.
>  *
>  * <p>The {@link #element()} and {@link #peek()} methods return, but do
>  * not remove, the head of the queue.
>  *
> - * <p>The <tt>Queue</tt> interface does not define the <i>blocking queue
> + * <p>The {@code Queue} interface does not define the <i>blocking queue
>  * methods</i>, which are common in concurrent programming.  These methods,
>  * which wait for elements to appear or for space to become available, are
>  * defined in the {@link java.util.concurrent.BlockingQueue} interface, which
>  * extends this interface.
>  *
> - * <p><tt>Queue</tt> implementations generally do not allow insertion
> - * of <tt>null</tt> elements, although some implementations, such as
> - * {@link LinkedList}, do not prohibit insertion of <tt>null</tt>.
> - * Even in the implementations that permit it, <tt>null</tt> should
> - * not be inserted into a <tt>Queue</tt>, as <tt>null</tt> is also
> - * used as a special return value by the <tt>poll</tt> method to
> + * <p>{@code Queue} implementations generally do not allow insertion
> + * of {@code null} elements, although some implementations, such as
> + * {@link LinkedList}, do not prohibit insertion of {@code null}.
> + * Even in the implementations that permit it, {@code null} should
> + * not be inserted into a {@code Queue}, as {@code null} is also
> + * used as a special return value by the {@code poll} method to
>  * indicate that the queue contains no elements.
>  *
> - * <p><tt>Queue</tt> implementations generally do not define
> - * element-based versions of methods <tt>equals</tt> and
> - * <tt>hashCode</tt> but instead inherit the identity based versions
> - * from class <tt>Object</tt>, because element-based equality is not
> + * <p>{@code Queue} implementations generally do not define
> + * element-based versions of methods {@code equals} and
> + * {@code hashCode} but instead inherit the identity based versions
> + * from class {@code Object}, because element-based equality is not
>  * always well-defined for queues with the same elements but different
>  * ordering properties.
>  *
> @@ -145,11 +146,11 @@ public interface Queue<E> extends Collec
>     /**
>      * Inserts the specified element into this queue if it is possible to do so
>      * immediately without violating capacity restrictions, returning
> -     * <tt>true</tt> upon success and throwing an <tt>IllegalStateException</tt>
> +     * {@code true} upon success and throwing an {@code IllegalStateException}
>      * if no space is currently available.
>      *
>      * @param e the element to add
> -     * @return <tt>true</tt> (as specified by {@link Collection#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
> @@ -169,8 +170,8 @@ public interface Queue<E> extends Collec
>      * by throwing an exception.
>      *
>      * @param e the element to add
> -     * @return <tt>true</tt> if the element was added to this queue, else
> -     *         <tt>false</tt>
> +     * @return {@code true} if the element was added to this queue, else
> +     *         {@code false}
>      * @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
> @@ -192,9 +193,9 @@ public interface Queue<E> extends Collec
> 
>     /**
>      * Retrieves and removes the head of this queue,
> -     * or returns <tt>null</tt> if this queue is empty.
> +     * or returns {@code null} if this queue is empty.
>      *
> -     * @return the head of this queue, or <tt>null</tt> if this queue is empty
> +     * @return the head of this queue, or {@code null} if this queue is empty
>      */
>     E poll();
> 
> @@ -210,9 +211,9 @@ public interface Queue<E> extends Collec
> 
>     /**
>      * Retrieves, but does not remove, the head of this queue,
> -     * or returns <tt>null</tt> if this queue is empty.
> +     * or returns {@code null} if this queue is empty.
>      *
> -     * @return the head of this queue, or <tt>null</tt> if this queue is empty
> +     * @return the head of this queue, or {@code null} if this queue is empty
>      */
>     E peek();
> }
> 
> -Chris.




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