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Java > Open Source Codes > net > nutch > mapReduce > RecordReader


1 /* Copyright (c) 2005 The Nutch Organization. All rights reserved. */
2 /* Use subject to the conditions in http://www.nutch.org/LICENSE.txt. */
3
4 package net.nutch.mapReduce;
5
6 import java.io.IOException JavaDoc;
7 import java.io.DataInput JavaDoc;
8
9 import net.nutch.io.Writable;
10
11 /** Reads key/value pairs from an input file {@link InputFormat.Split}.
12  * Implemented by {@link InputFormat} implementations. */
13 public interface RecordReader {
14
15   /** Constructs a key suitable to pass as the first parameter to {@link
16    * #next(Writable,Writable)}. */
17   Writable createKey();
18
19   /** Constructs a value suitable to pass as the second parameter to {@link
20    * #next(Writable,Writable)}. */
21   Writable createValue();
22
23   /** Reads the next key/value pair.
24    *
25    * @param key the key to read data into
26    * @param value the value to read data into
27    * @return true iff a key/value was read, false if at EOF
28    *
29    * @see Writable#readFields(DataInput)
30    */
31   boolean next(Writable key, Writable value) throws IOException JavaDoc;
32 }
33
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