8 |
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|
9 |
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/** |
10 |
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* A collection designed for holding elements prior to processing. |
11 |
< |
* Besides basic {@link java.util.Collection Collection} operations, queues provide |
12 |
< |
* additional insertion, extraction, and inspection operations. |
11 |
> |
* Besides basic {@link java.util.Collection Collection} operations, |
12 |
> |
* queues provide additional insertion, extraction, and inspection |
13 |
> |
* operations. Each of these methods exists in two forms: one throws |
14 |
> |
* an exception if the operation fails, the other returns a special |
15 |
> |
* value (either <tt>null</tt> or <tt>false</tt>, depending on the |
16 |
> |
* operation). The latter form of the insert operation is designed |
17 |
> |
* specifically for use with capacity-restricted <tt>Queue</tt> |
18 |
> |
* implementations; in most implementations, insert operations cannot |
19 |
> |
* fail. |
20 |
> |
* |
21 |
> |
* <p> |
22 |
> |
* <table BORDER CELLPADDING=3 CELLSPACING=1> |
23 |
> |
* <tr> |
24 |
> |
* <td></td> |
25 |
> |
* <td ALIGN=CENTER><em>Throws exception</em></td> |
26 |
> |
* <td ALIGN=CENTER><em>Returns special value</em></td> |
27 |
> |
* </tr> |
28 |
> |
* <tr> |
29 |
> |
* <td><b>Insert</b></td> |
30 |
> |
* <td>{@link #add add(e)}</td> |
31 |
> |
* <td>{@link #offer offer(e)}</td> |
32 |
> |
* </tr> |
33 |
> |
* <tr> |
34 |
> |
* <td><b>Remove</b></td> |
35 |
> |
* <td>{@link #remove remove()}</td> |
36 |
> |
* <td>{@link #poll poll()}</td> |
37 |
> |
* </tr> |
38 |
> |
* <tr> |
39 |
> |
* <td><b>Examine</b></td> |
40 |
> |
* <td>{@link #element element()}</td> |
41 |
> |
* <td>{@link #peek peek()}</td> |
42 |
> |
* </tr> |
43 |
> |
* </table> |
44 |
|
* |
45 |
|
* <p>Queues typically, but do not necessarily, order elements in a |
46 |
|
* FIFO (first-in-first-out) manner. Among the exceptions are |
121 |
|
* preferable to method {@link Collection#add}, which can fail to |
122 |
|
* insert an element only by throwing an exception. |
123 |
|
* |
124 |
< |
* @param o the element to insert. |
124 |
> |
* @param e the element to insert. |
125 |
|
* @return <tt>true</tt> if it was possible to add the element to |
126 |
|
* this queue, else <tt>false</tt> |
127 |
|
*/ |
128 |
< |
boolean offer(E o); |
128 |
> |
boolean offer(E e); |
129 |
|
|
130 |
|
/** |
131 |
|
* Retrieves and removes the head of this queue, or <tt>null</tt> |
138 |
|
|
139 |
|
/** |
140 |
|
* Retrieves and removes the head of this queue. This method |
141 |
< |
* differs from the <tt>poll</tt> method in that it throws an |
141 |
> |
* differs from the {@link #poll} method only in that it throws an |
142 |
|
* exception if this queue is empty. |
143 |
|
* |
144 |
|
* @return the head of this queue. |
157 |
|
|
158 |
|
/** |
159 |
|
* Retrieves, but does not remove, the head of this queue. This method |
160 |
< |
* differs from the <tt>peek</tt> method only in that it throws an |
160 |
> |
* differs from the {@link #peek} method only in that it throws an |
161 |
|
* exception if this queue is empty. |
162 |
|
* |
163 |
|
* @return the head of this queue. |