ValueAggregator (Apache Hadoop Main 3.5.0 API)
Description: declaration: package: org.apache.hadoop.mapreduce.lib.aggregate, interface: ValueAggregator

Package org.apache.hadoop.mapreduce.lib.aggregate

# Interface ValueAggregator<E>

All Known Subinterfaces:
  `ValueAggregator<E>`

All Known Implementing Classes:
  `DoubleValueSum`, `DoubleValueSum`, `LongValueMax`, `LongValueMax`, `LongValueMin`, `LongValueMin`, `LongValueSum`, `LongValueSum`, `StringValueMax`, `StringValueMax`, `StringValueMin`, `StringValueMin`, `UniqValueCount`, `UniqValueCount`, `ValueHistogram`, `ValueHistogram`

@Public @Stable public interface ValueAggregator<E>
This interface defines the minimal protocol for value aggregators.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `addNextValue(Object val)`
  add a value to the aggregator
  `ArrayList<E>`
  `getCombinerOutput()`
  `String`
  `getReport()`
  `void`
  `reset()`
  reset the aggregator

- ## Method Details

  - ### addNextValue

    void addNextValue(Object val)
    add a value to the aggregator
    Parameters:
      `val` - the value to be added

  - ### reset

    void reset()
    reset the aggregator

  - ### getReport

    String getReport()
    Returns:
      the string representation of the agregator

  - ### getCombinerOutput

    ArrayList<E> getCombinerOutput()
    Returns:
      an array of values as the outputs of the combiner.