1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * https://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 */
20 package org.apache.directory.api.util;
21
22
23 import javax.naming.NamingEnumeration;
24
25 import java.util.NoSuchElementException;
26
27
28 /**
29 * A NamingEnumeration over a single element.
30 *
31 * @param <T> The element in the enumeration
32 *
33 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
34 */
35 public class SingletonEnumeration<T> implements NamingEnumeration<T>
36 {
37 /** The singleton element to return */
38 private final T element;
39
40 /** Can we return a element */
41 private boolean hasMore = true;
42
43
44 /**
45 * Creates a NamingEnumeration over a single element.
46 *
47 * @param element The element to store in this enumeration
48 */
49 public SingletonEnumeration( final T element )
50 {
51 this.element = element;
52 }
53
54
55 /**
56 * Makes calls to hasMore to false even if we had more.
57 *
58 * @see javax.naming.NamingEnumeration#close()
59 */
60 @Override
61 public void close()
62 {
63 hasMore = false;
64 }
65
66
67 /**
68 * @see javax.naming.NamingEnumeration#hasMore()
69 */
70 @Override
71 public boolean hasMore()
72 {
73 return hasMore;
74 }
75
76
77 /**
78 * @see javax.naming.NamingEnumeration#next()
79 */
80 @Override
81 public T next()
82 {
83 if ( hasMore )
84 {
85 hasMore = false;
86 return element;
87 }
88
89 throw new NoSuchElementException();
90 }
91
92
93 /**
94 * @see java.util.Enumeration#hasMoreElements()
95 */
96 @Override
97 public boolean hasMoreElements()
98 {
99 return hasMore;
100 }
101
102
103 /**
104 * @see java.util.Enumeration#nextElement()
105 */
106 @Override
107 public T nextElement()
108 {
109 return next();
110 }
111 }