Uses of Class org.apache.hadoop.mapreduce.Reducer (Apache Hadoop Main 3.5.0 API)
Description: use: package: org.apache.hadoop.mapreduce, class: Reducer

# Uses of Class
org.apache.hadoop.mapreduce.Reducer

Packages that use Reducer
Package
Description
org.apache.hadoop.mapreduce
org.apache.hadoop.mapreduce.lib.aggregate
org.apache.hadoop.mapreduce.lib.chain
org.apache.hadoop.mapreduce.lib.fieldsel
org.apache.hadoop.mapreduce.lib.reduce

- ## Uses of Reducer in org.apache.hadoop.mapreduce

  Methods in org.apache.hadoop.mapreduce that return types with arguments of type Reducer
  Modifier and Type
  Method
  Description
  `Class<? extends Reducer<?,?,?,?>>`
  JobContext.`getCombinerClass()`
  Get the combiner class for the job.
  `Class<? extends Reducer<?,?,?,?>>`
  JobContext.`getReducerClass()`
  Get the `Reducer` class for the job.
  Method parameters in org.apache.hadoop.mapreduce with type arguments of type Reducer
  Modifier and Type
  Method
  Description
  `void`
  Job.`setCombinerClass(Class<? extends Reducer> cls)`
  Set the combiner class for the job.
  `void`
  Job.`setReducerClass(Class<? extends Reducer> cls)`
  Set the `Reducer` for the job.

- ## Uses of Reducer in org.apache.hadoop.mapreduce.lib.aggregate

  Subclasses of Reducer in org.apache.hadoop.mapreduce.lib.aggregate
  Modifier and Type
  Class
  Description
  `class`
  `ValueAggregatorCombiner<K1 extends WritableComparable<?>,V1 extends Writable>`
  This class implements the generic combiner of Aggregate.
  `class`
  `ValueAggregatorReducer<K1 extends WritableComparable<?>,V1 extends Writable>`
  This class implements the generic reducer of Aggregate.

- ## Uses of Reducer in org.apache.hadoop.mapreduce.lib.chain

  Subclasses of Reducer in org.apache.hadoop.mapreduce.lib.chain
  Modifier and Type
  Class
  Description
  `class`
  `ChainReducer<KEYIN,VALUEIN,KEYOUT,VALUEOUT>`
  The ChainReducer class allows to chain multiple Mapper classes after a Reducer within the Reducer task.
  Method parameters in org.apache.hadoop.mapreduce.lib.chain with type arguments of type Reducer
  Modifier and Type
  Method
  Description
  `static void`
  ChainReducer.`setReducer(Job job, Class<? extends Reducer> klass, Class<?> inputKeyClass, Class<?> inputValueClass, Class<?> outputKeyClass, Class<?> outputValueClass, Configuration reducerConf)`
  Sets the `Reducer` class to the chain job.

- ## Uses of Reducer in org.apache.hadoop.mapreduce.lib.fieldsel

  Subclasses of Reducer in org.apache.hadoop.mapreduce.lib.fieldsel
  Modifier and Type
  Class
  Description
  `class`
  `FieldSelectionReducer<K,V>`
  This class implements a reducer class that can be used to perform field selections in a manner similar to unix cut.

- ## Uses of Reducer in org.apache.hadoop.mapreduce.lib.reduce

  Subclasses of Reducer in org.apache.hadoop.mapreduce.lib.reduce
  Modifier and Type
  Class
  Description
  `class`
  `IntSumReducer<Key>`
  `class`
  `LongSumReducer<KEY>`
  `class`
  `WrappedReducer<KEYIN,VALUEIN,KEYOUT,VALUEOUT>`
  A `Reducer` which wraps a given one to allow for custom `Reducer.Context` implementations.