IndexHashGrouping (Storm 2.7.1 API)

java.lang.Object
- org.apache.storm.trident.partition.IndexHashGrouping

All Implemented Interfaces:

Serializable, CustomStreamGrouping
```
public class IndexHashGrouping
extends Object
implements CustomStreamGrouping
```
See Also:

Serialized Form

Constructor Summary

Constructors
Constructor Description

IndexHashGrouping(int index)

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`List<Integer>`	`chooseTasks(int fromTask, List<Object> values)`	This function implements a custom stream grouping.
`static int`	`objectToIndex(Object val, int numPartitions)`
`void`	`prepare(WorkerTopologyContext context, GlobalStreamId stream, List<Integer> targetTasks)`	Tells the stream grouping at runtime the tasks in the target bolt.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - IndexHashGrouping
```
public IndexHashGrouping(int index)
```
- Method Detail
  - objectToIndex
```
public static int objectToIndex(Object val,
                                int numPartitions)
```
  - prepare
```
public void prepare(WorkerTopologyContext context,
                    GlobalStreamId stream,
                    List<Integer> targetTasks)
```
    Description copied from interface: CustomStreamGrouping
    
    Tells the stream grouping at runtime the tasks in the target bolt. This information should be used in chooseTasks to determine the target tasks.
    It also tells the grouping the metadata on the stream this grouping will be used on.
    
    Specified by:
    
    prepare in interface CustomStreamGrouping
  - chooseTasks
```
public List<Integer> chooseTasks(int fromTask,
                                 List<Object> values)
```
    Description copied from interface: CustomStreamGrouping
    
    This function implements a custom stream grouping. It takes in as input the number of tasks in the target bolt in prepare and returns the tasks to send the tuples to.
    
    Specified by:
    
    chooseTasks in interface CustomStreamGrouping
    
    values - the values to group on