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| <h2 title="Interface RecordReader" class="title">Interface RecordReader<K,V></h2> |
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| <dt>All Superinterfaces:</dt> |
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| </dl> |
| <dl> |
| <dt>All Known Subinterfaces:</dt> |
| <dd><a href="../../../../org/apache/hadoop/mapred/join/ComposableRecordReader.html" title="interface in org.apache.hadoop.mapred.join">ComposableRecordReader</a><K,V></dd> |
| </dl> |
| <dl> |
| <dt>All Known Implementing Classes:</dt> |
| <dd><a href="../../../../org/apache/hadoop/mapred/lib/CombineFileRecordReader.html" title="class in org.apache.hadoop.mapred.lib">CombineFileRecordReader</a>, <a href="../../../../org/apache/hadoop/mapred/lib/CombineFileRecordReaderWrapper.html" title="class in org.apache.hadoop.mapred.lib">CombineFileRecordReaderWrapper</a>, <a href="../../../../org/apache/hadoop/mapred/join/InnerJoinRecordReader.html" title="class in org.apache.hadoop.mapred.join">InnerJoinRecordReader</a>, <a href="../../../../org/apache/hadoop/mapred/join/JoinRecordReader.html" title="class in org.apache.hadoop.mapred.join">JoinRecordReader</a>, <a href="../../../../org/apache/hadoop/mapred/KeyValueLineRecordReader.html" title="class in org.apache.hadoop.mapred">KeyValueLineRecordReader</a>, <a href="../../../../org/apache/hadoop/mapred/join/MultiFilterRecordReader.html" title="class in org.apache.hadoop.mapred.join">MultiFilterRecordReader</a>, <a href="../../../../org/apache/hadoop/mapred/join/OuterJoinRecordReader.html" title="class in org.apache.hadoop.mapred.join">OuterJoinRecordReader</a>, <a href="../../../../org/apache/hadoop/mapred/join/OverrideRecordReader.html" title="class in org.apache.hadoop.mapred.join">OverrideRecordReader</a>, <a href="../../../../org/apache/hadoop/mapred/SequenceFileAsTextRecordReader.html" title="class in org.apache.hadoop.mapred">SequenceFileAsTextRecordReader</a>, <a href="../../../../org/apache/hadoop/mapred/SequenceFileRecordReader.html" title="class in org.apache.hadoop.mapred">SequenceFileRecordReader</a>, <a href="../../../../org/apache/hadoop/mapred/join/WrappedRecordReader.html" title="class in org.apache.hadoop.mapred.join">WrappedRecordReader</a></dd> |
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| <hr> |
| <br> |
| <pre>@InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public interface <span class="typeNameLabel">RecordReader<K,V></span> |
| extends <a href="https://docs.oracle.com/javase/8/docs/api/java/io/Closeable.html?is-external=true" title="class or interface in java.io">Closeable</a></pre> |
| <div class="block"><code>RecordReader</code> reads <key, value> pairs from an |
| <a href="../../../../org/apache/hadoop/mapred/InputSplit.html" title="interface in org.apache.hadoop.mapred"><code>InputSplit</code></a>. |
| |
| <p><code>RecordReader</code>, typically, converts the byte-oriented view of |
| the input, provided by the <code>InputSplit</code>, and presents a |
| record-oriented view for the <a href="../../../../org/apache/hadoop/mapred/Mapper.html" title="interface in org.apache.hadoop.mapred"><code>Mapper</code></a> and <a href="../../../../org/apache/hadoop/mapred/Reducer.html" title="interface in org.apache.hadoop.mapred"><code>Reducer</code></a> tasks for |
| processing. It thus assumes the responsibility of processing record |
| boundaries and presenting the tasks with keys and values.</p></div> |
| <dl> |
| <dt><span class="seeLabel">See Also:</span></dt> |
| <dd><a href="../../../../org/apache/hadoop/mapred/InputSplit.html" title="interface in org.apache.hadoop.mapred"><code>InputSplit</code></a>, |
| <a href="../../../../org/apache/hadoop/mapred/InputFormat.html" title="interface in org.apache.hadoop.mapred"><code>InputFormat</code></a></dd> |
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| <h3>Method Summary</h3> |
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| <caption><span id="t0" class="activeTableTab"><span>All Methods</span><span class="tabEnd"> </span></span><span id="t2" class="tableTab"><span><a href="javascript:show(2);">Instance Methods</a></span><span class="tabEnd"> </span></span><span id="t3" class="tableTab"><span><a href="javascript:show(4);">Abstract Methods</a></span><span class="tabEnd"> </span></span></caption> |
| <tr> |
| <th class="colFirst" scope="col">Modifier and Type</th> |
| <th class="colLast" scope="col">Method and Description</th> |
| </tr> |
| <tr id="i0" class="altColor"> |
| <td class="colFirst"><code>void</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../org/apache/hadoop/mapred/RecordReader.html#close--">close</a></span>()</code> |
| <div class="block">Close this <a href="../../../../org/apache/hadoop/mapred/InputSplit.html" title="interface in org.apache.hadoop.mapred"><code>InputSplit</code></a> to future operations.</div> |
| </td> |
| </tr> |
| <tr id="i1" class="rowColor"> |
| <td class="colFirst"><code><a href="../../../../org/apache/hadoop/mapred/RecordReader.html" title="type parameter in RecordReader">K</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../org/apache/hadoop/mapred/RecordReader.html#createKey--">createKey</a></span>()</code> |
| <div class="block">Create an object of the appropriate type to be used as a key.</div> |
| </td> |
| </tr> |
| <tr id="i2" class="altColor"> |
| <td class="colFirst"><code><a href="../../../../org/apache/hadoop/mapred/RecordReader.html" title="type parameter in RecordReader">V</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../org/apache/hadoop/mapred/RecordReader.html#createValue--">createValue</a></span>()</code> |
| <div class="block">Create an object of the appropriate type to be used as a value.</div> |
| </td> |
| </tr> |
| <tr id="i3" class="rowColor"> |
| <td class="colFirst"><code>long</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../org/apache/hadoop/mapred/RecordReader.html#getPos--">getPos</a></span>()</code> |
| <div class="block">Returns the current position in the input.</div> |
| </td> |
| </tr> |
| <tr id="i4" class="altColor"> |
| <td class="colFirst"><code>float</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../org/apache/hadoop/mapred/RecordReader.html#getProgress--">getProgress</a></span>()</code> |
| <div class="block">How much of the input has the <a href="../../../../org/apache/hadoop/mapred/RecordReader.html" title="interface in org.apache.hadoop.mapred"><code>RecordReader</code></a> consumed i.e.</div> |
| </td> |
| </tr> |
| <tr id="i5" class="rowColor"> |
| <td class="colFirst"><code>boolean</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../org/apache/hadoop/mapred/RecordReader.html#next-K-V-">next</a></span>(<a href="../../../../org/apache/hadoop/mapred/RecordReader.html" title="type parameter in RecordReader">K</a> key, |
| <a href="../../../../org/apache/hadoop/mapred/RecordReader.html" title="type parameter in RecordReader">V</a> value)</code> |
| <div class="block">Reads the next key/value pair from the input for processing.</div> |
| </td> |
| </tr> |
| </table> |
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| <pre>boolean next(<a href="../../../../org/apache/hadoop/mapred/RecordReader.html" title="type parameter in RecordReader">K</a> key, |
| <a href="../../../../org/apache/hadoop/mapred/RecordReader.html" title="type parameter in RecordReader">V</a> value) |
| throws <a href="https://docs.oracle.com/javase/8/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</a></pre> |
| <div class="block">Reads the next key/value pair from the input for processing.</div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>key</code> - the key to read data into</dd> |
| <dd><code>value</code> - the value to read data into</dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>true iff a key/value was read, false if at EOF</dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code><a href="https://docs.oracle.com/javase/8/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</a></code></dd> |
| </dl> |
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| <li class="blockList"> |
| <h4>createKey</h4> |
| <pre><a href="../../../../org/apache/hadoop/mapred/RecordReader.html" title="type parameter in RecordReader">K</a> createKey()</pre> |
| <div class="block">Create an object of the appropriate type to be used as a key.</div> |
| <dl> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>a new key object.</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="createValue--"> |
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| <h4>createValue</h4> |
| <pre><a href="../../../../org/apache/hadoop/mapred/RecordReader.html" title="type parameter in RecordReader">V</a> createValue()</pre> |
| <div class="block">Create an object of the appropriate type to be used as a value.</div> |
| <dl> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>a new value object.</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="getPos--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>getPos</h4> |
| <pre>long getPos() |
| throws <a href="https://docs.oracle.com/javase/8/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</a></pre> |
| <div class="block">Returns the current position in the input.</div> |
| <dl> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>the current position in the input.</dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code><a href="https://docs.oracle.com/javase/8/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</a></code></dd> |
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| <h4>close</h4> |
| <pre>void close() |
| throws <a href="https://docs.oracle.com/javase/8/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</a></pre> |
| <div class="block">Close this <a href="../../../../org/apache/hadoop/mapred/InputSplit.html" title="interface in org.apache.hadoop.mapred"><code>InputSplit</code></a> to future operations.</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code><a href="https://docs.oracle.com/javase/8/docs/api/java/lang/AutoCloseable.html?is-external=true#close--" title="class or interface in java.lang">close</a></code> in interface <code><a href="https://docs.oracle.com/javase/8/docs/api/java/lang/AutoCloseable.html?is-external=true" title="class or interface in java.lang">AutoCloseable</a></code></dd> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code><a href="https://docs.oracle.com/javase/8/docs/api/java/io/Closeable.html?is-external=true#close--" title="class or interface in java.io">close</a></code> in interface <code><a href="https://docs.oracle.com/javase/8/docs/api/java/io/Closeable.html?is-external=true" title="class or interface in java.io">Closeable</a></code></dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code><a href="https://docs.oracle.com/javase/8/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</a></code></dd> |
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| <h4>getProgress</h4> |
| <pre>float getProgress() |
| throws <a href="https://docs.oracle.com/javase/8/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</a></pre> |
| <div class="block">How much of the input has the <a href="../../../../org/apache/hadoop/mapred/RecordReader.html" title="interface in org.apache.hadoop.mapred"><code>RecordReader</code></a> consumed i.e. |
| has been processed by?</div> |
| <dl> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>progress from <code>0.0</code> to <code>1.0</code>.</dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code><a href="https://docs.oracle.com/javase/8/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</a></code></dd> |
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