HashPartitioner (Apache Hadoop Main 3.5.0 API)
Description: declaration: package: org.apache.hadoop.mapreduce.lib.partition, class: HashPartitioner

Package org.apache.hadoop.mapreduce.lib.partition

# Class HashPartitioner<K,V>

java.lang.Object
org.apache.hadoop.mapreduce.Partitioner<K,V>
org.apache.hadoop.mapreduce.lib.partition.HashPartitioner<K,V>

@Public @Stable public class HashPartitioner<K,V> extends Partitioner<K,V>
Partition keys by their `Object.hashCode()`.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `HashPartitioner()`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `int`
  `getPartition(K key, V value, int numReduceTasks)`
  Use `Object.hashCode()` to partition.

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### HashPartitioner

    public HashPartitioner()

- ## Method Details

  - ### getPartition

    public int getPartition(K key, V value, int numReduceTasks)
    Use `Object.hashCode()` to partition.
    Specified by:
      `getPartition` in class `Partitioner<K,V>`
    Parameters:
      `key` - the key to be partioned.
      `value` - the entry value.
      `numReduceTasks` - the total number of partitions.
    Returns:
      the partition number for the `key`.