1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.jetspeed.util;
19
20 /***
21 * Simple FIFO implementation of Queue interface extending Vector
22 * as storage backend.
23 *
24 * @author <a href="mailto:raphael@apache.org">Rapha\u00ebl Luta</a>
25 * @version $Id: FIFOQueue.java 516448 2007-03-09 16:25:47Z ate $
26 */
27 public class FIFOQueue extends java.util.Vector implements Queue
28 {
29 /***
30 * Adds a new object into the queue
31 */
32 public synchronized void push(Object obj)
33 {
34 this.add(obj);
35 }
36
37 /***
38 * Gets the first object in the queue and remove it from the queue
39 */
40 public synchronized Object pop()
41 {
42
43 if (this.size() == 0)
44 {
45 return null;
46 }
47
48 return this.remove(0);
49 }
50
51 /***
52 * Gets the first object in the queue without removing it from the queue
53 */
54 public synchronized Object peek()
55 {
56
57 if (this.size() == 0)
58 {
59 return null;
60 }
61
62 return this.get(0);
63 }
64 }