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java.lang.Objectorg.apache.hadoop.mapred.MapReduceBase
org.apache.hadoop.examples.MultiFileWordCount.MapClass
public static class MultiFileWordCount.MapClass
This Mapper is similar to the one in MultiFileWordCount.MapClass
.
Constructor Summary | |
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MultiFileWordCount.MapClass()
|
Method Summary | |
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void |
map(MultiFileWordCount.WordOffset key,
Text value,
OutputCollector<Text,IntWritable> output,
Reporter reporter)
Maps a single input key/value pair into an intermediate key/value pair. |
Methods inherited from class org.apache.hadoop.mapred.MapReduceBase |
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close, configure |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface org.apache.hadoop.mapred.JobConfigurable |
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configure |
Methods inherited from interface java.io.Closeable |
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close |
Constructor Detail |
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public MultiFileWordCount.MapClass()
Method Detail |
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public void map(MultiFileWordCount.WordOffset key, Text value, OutputCollector<Text,IntWritable> output, Reporter reporter) throws java.io.IOException
Mapper
Output pairs need not be of the same types as input pairs. A given
input pair may map to zero or many output pairs. Output pairs are
collected with calls to
OutputCollector.collect(Object,Object)
.
Applications can use the Reporter
provided to report progress
or just indicate that they are alive. In scenarios where the application
takes an insignificant amount of time to process individual key/value
pairs, this is crucial since the framework might assume that the task has
timed-out and kill that task. The other way of avoiding this is to set
mapred.task.timeout to a high-enough value (or even zero for no
time-outs).
map
in interface Mapper<MultiFileWordCount.WordOffset,Text,Text,IntWritable>
key
- the input key.value
- the input value.output
- collects mapped keys and values.reporter
- facility to report progress.
java.io.IOException
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