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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 static org.apache.commons.io.IOUtils.EOF;
20  
21  import java.io.InputStream;
22  
23  import org.apache.commons.io.IOUtils;
24  
25  /**
26   * Always returns {@link IOUtils#EOF} to all attempts to read something from the stream.
27   * <p>
28   * Typically uses of this class include testing for corner cases in methods that accept input streams and acting as a
29   * sentinel value instead of a {@code null} input stream.
30   * </p>
31   *
32   * @since 1.4
33   */
34  public class ClosedInputStream extends InputStream {
35  
36      /**
37       * The singleton instance.
38       *
39       * @since 2.12.0
40       */
41      public static final ClosedInputStream INSTANCE = new ClosedInputStream();
42  
43      /**
44       * The singleton instance.
45       *
46       * @deprecated Use {@link #INSTANCE}.
47       */
48      @Deprecated
49      public static final ClosedInputStream CLOSED_INPUT_STREAM = INSTANCE;
50  
51      /**
52       * Returns -1 to indicate that the stream is closed.
53       *
54       * @return always -1
55       */
56      @Override
57      public int read() {
58          return EOF;
59      }
60  
61  }