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.io.input;
18 
19 import java.io.InputStream;
20 
21 /**
22  * Closed input stream. This stream returns -1 to all attempts to read
23  * something from the stream.
24  * <p>
25  * Typically uses of this class include testing for corner cases in methods
26  * that accept input streams and acting as a sentinel value instead of a
27  * <code>null</code> input stream.
28  *
29  * @version $Id: ClosedInputStream.java 601751 2007-12-06 14:55:45Z niallp $
30  * @since Commons IO 1.4
31  */
32 public class ClosedInputStream extends InputStream {
33 
34     /**
35      * A singleton.
36      */
37     public static final ClosedInputStream CLOSED_INPUT_STREAM = new ClosedInputStream();
38 
39     /**
40      * Returns -1 to indicate that the stream is closed.
41      *
42      * @return always -1
43      */
read()44     public int read() {
45         return -1;
46     }
47 
48 }
49