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 * http://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 package org.apache.directory.server.core.cursor;
20
21
22 /**
23 * An empty Cursor implementation.
24 *
25 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
26 * @version $Rev$, $Date$
27 */
28 public class EmptyCursor<E> extends AbstractCursor<E>
29 {
30 public boolean available()
31 {
32 return false;
33 }
34
35 public void before( E element ) throws Exception
36 {
37 checkNotClosed( "before()" );
38 }
39
40
41 public void after( E element ) throws Exception
42 {
43 checkNotClosed( "after()" );
44 }
45
46
47 public void beforeFirst() throws Exception
48 {
49 checkNotClosed( "beforeFirst()" );
50 }
51
52
53 public void afterLast() throws Exception
54 {
55 checkNotClosed( "afterLast()" );
56 }
57
58
59 public boolean first() throws Exception
60 {
61 checkNotClosed( "first()" );
62 return false;
63 }
64
65
66 public boolean last() throws Exception
67 {
68 checkNotClosed( "last()" );
69 return false;
70 }
71
72
73 public boolean previous() throws Exception
74 {
75 checkNotClosed( "previous()" );
76 return false;
77 }
78
79
80 public boolean next() throws Exception
81 {
82 checkNotClosed( "next()" );
83 return false;
84 }
85
86
87 public E get() throws Exception
88 {
89 checkNotClosed( "get()" );
90 throw new InvalidCursorPositionException( "This cursor is empty and cannot return elements!" );
91 }
92
93
94 public boolean isElementReused()
95 {
96 return false;
97 }
98 }