001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package org.apache.hadoop.mapred;
020    
021    import java.io.IOException;
022    
023    import org.apache.hadoop.classification.InterfaceAudience;
024    import org.apache.hadoop.classification.InterfaceStability;
025    import org.apache.hadoop.fs.FileSystem;
026    
027    /**
028     * <code>RecordWriter</code> writes the output &lt;key, value&gt; pairs 
029     * to an output file.
030     
031     * <p><code>RecordWriter</code> implementations write the job outputs to the
032     * {@link FileSystem}.
033     * 
034     * @see OutputFormat
035     */
036    @InterfaceAudience.Public
037    @InterfaceStability.Stable
038    public interface RecordWriter<K, V> {
039      /** 
040       * Writes a key/value pair.
041       *
042       * @param key the key to write.
043       * @param value the value to write.
044       * @throws IOException
045       */      
046      void write(K key, V value) throws IOException;
047    
048      /** 
049       * Close this <code>RecordWriter</code> to future operations.
050       * 
051       * @param reporter facility to report progress.
052       * @throws IOException
053       */ 
054      void close(Reporter reporter) throws IOException;
055    }