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Java > Open Source Codes > org > apache > commons > collections > primitives > adapters > io > ReaderCharIterator


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 package org.apache.commons.collections.primitives.adapters.io;
18
19 import java.io.IOException JavaDoc;
20 import java.io.Reader JavaDoc;
21 import java.util.NoSuchElementException JavaDoc;
22
23 import org.apache.commons.collections.primitives.CharIterator;
24
25 /**
26  * Adapts a {@link Reader} to the {@link CharIterator} interface.
27  *
28  * @version $Revision: 480462 $ $Date: 2006-11-29 00:15:00 -0800 (Wed, 29 Nov 2006) $
29  * @author Rodney Waldhoff
30  */
31 public class ReaderCharIterator implements CharIterator {
32
33     public ReaderCharIterator(Reader JavaDoc in) {
34         this.reader = in;
35     }
36
37     public static CharIterator adapt(Reader JavaDoc in) {
38         return null == in ? null : new ReaderCharIterator(in);
39     }
40     
41     public boolean hasNext() {
42         ensureNextAvailable();
43         return (-1 != next);
44     }
45
46     public char next() {
47         if(!hasNext()) {
48             throw new NoSuchElementException JavaDoc("No next element");
49         } else {
50             nextAvailable = false;
51             return (char)next;
52         }
53     }
54     
55     /**
56      * Not supported.
57      * @throws UnsupportedOperationException
58      */
59     public void remove() throws UnsupportedOperationException JavaDoc {
60         throw new UnsupportedOperationException JavaDoc("remove() is not supported here");
61     }
62
63     private void ensureNextAvailable() {
64         if(!nextAvailable) {
65             readNext();
66         }
67     }
68
69     private void readNext() {
70         try {
71             next = reader.read();
72             nextAvailable = true;
73         } catch(IOException JavaDoc e) {
74             // TODO: Use a tunnelled exception instead?
75 // See http://radio.weblogs.com/0122027/2003/04/01.html#a7, for example
76 throw new RuntimeException JavaDoc(e.toString());
77         }
78     }
79     
80     private Reader JavaDoc reader = null;
81     private boolean nextAvailable = false;
82     private int next;
83
84 }
85
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