| 16 |
|
* priority queues, which order elements according to a supplied |
| 17 |
|
* comparator, or the elements' natural ordering, and LIFO queues (or |
| 18 |
|
* stacks) which order the elements LIFO (last-in-first-out). |
| 19 |
< |
* Whatever the ordering used, the <em>head</em> of the queue is that element |
| 20 |
< |
* which would be removed by a call to {@link #remove() } or {@link #poll()}. |
| 21 |
< |
* Every <tt>Queue</tt> implementation must specify its ordering guarantees. |
| 22 |
< |
* |
| 23 |
< |
* <p>The {@link #offer offer} method adds an element if possible, otherwise |
| 24 |
< |
* returning <tt>false</tt>. This differs from the |
| 25 |
< |
* {@link java.util.Collection#add Collection.add} |
| 26 |
< |
* method, which throws an unchecked exception upon |
| 27 |
< |
* failure. It is designed for use in collections in which failure to |
| 28 |
< |
* add is a normal, rather than exceptional occurrence, for example, |
| 29 |
< |
* in fixed-capacity (or "bounded") queues. |
| 19 |
> |
* Whatever the ordering used, the <em>head</em> of the queue is that |
| 20 |
> |
* element which would be removed by a call to {@link #remove() } or |
| 21 |
> |
* {@link #poll()}. In a FIFO queue, all new elements are inserted at |
| 22 |
> |
* the <em> tail</em> of the queue. Other kinds of queues may use |
| 23 |
> |
* different placement rules. Every <tt>Queue</tt> implementation |
| 24 |
> |
* must specify its ordering properties. |
| 25 |
> |
* |
| 26 |
> |
* <p>The {@link #offer offer} method inserts an element if possible, |
| 27 |
> |
* otherwise returning <tt>false</tt>. This differs from the {@link |
| 28 |
> |
* java.util.Collection#add Collection.add} method, which can fail to |
| 29 |
> |
* add an element only by throwing an unchecked exception. The |
| 30 |
> |
* <tt>offer</tt> method is designed for use when failure is a normal, |
| 31 |
> |
* rather than exceptional occurrence, for example, in fixed-capacity |
| 32 |
> |
* (or "bounded") queues. |
| 33 |
|
* |
| 34 |
|
* <p>The {@link #remove()} and {@link #poll()} methods remove and |
| 35 |
|
* return the head of the queue. |
| 83 |
|
public interface Queue<E> extends Collection<E> { |
| 84 |
|
|
| 85 |
|
/** |
| 86 |
< |
* Adds the specified element to this queue, if possible. |
| 86 |
> |
* Inserts the specified element to this queue, if possible. When |
| 87 |
> |
* using queues that may impose insertion restrictions (for |
| 88 |
> |
* example capacity bounds), method <tt>offer</tt> is generally |
| 89 |
> |
* preferable to method {@link Collection#add}, which can fail to |
| 90 |
> |
* insert an element only by throwing an exception. |
| 91 |
|
* |
| 92 |
< |
* @param o the element to add. |
| 92 |
> |
* @param o the element to insert. |
| 93 |
|
* @return <tt>true</tt> if it was possible to add the element to |
| 94 |
|
* this queue, else <tt>false</tt> |
| 95 |
|
*/ |
| 134 |
|
*/ |
| 135 |
|
E element(); |
| 136 |
|
} |
| 130 |
– |
|
| 131 |
– |
|
| 132 |
– |
|
| 133 |
– |
|
| 134 |
– |
|
| 135 |
– |
|
| 136 |
– |
|
| 137 |
– |
|
| 138 |
– |
|
| 139 |
– |
|
