GroupingState (core 2.44.0 API)

Type Parameters:

InputT - the type of values added to the state

OutputT - the type of value extracted from the state

All Superinterfaces:

ReadableState<OutputT>, State

All Known Subinterfaces:

BagState<T>, CombiningState<InputT,AccumT,OutputT>, OrderedListState<T>, SetState<T>, WatermarkHoldState
```
@Experimental(STATE)
public interface GroupingState<InputT,OutputT>
extends ReadableState<OutputT>, State
```
A ReadableState cell that combines multiple input values and outputs a single value of a different type.
This generalizes GroupByKey and Combine styles of grouping.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`add(InputT value)`	Add a value to the buffer.
`ReadableState<java.lang.Boolean>`	`isEmpty()`	Returns a `ReadableState` whose `ReadableState.read()` method will return true if this state is empty at the point when that `ReadableState.read()` call returns.
`GroupingState<InputT,OutputT>`	`readLater()`	Indicate that the value will be read later.

Methods inherited from interface org.apache.beam.sdk.state.ReadableState
read

Methods inherited from interface org.apache.beam.sdk.state.State
clear

- Method Detail
  - add
```
void add(InputT value)
```
    Add a value to the buffer.
    Elements added will not be reflected in OutputT objects returned by previous calls to ReadableState.read().
  - isEmpty
```
ReadableState<java.lang.Boolean> isEmpty()
```
    Returns a ReadableState whose ReadableState.read() method will return true if this state is empty at the point when that ReadableState.read() call returns.
  - readLater
```
GroupingState<InputT,OutputT> readLater()
```
    Description copied from interface: ReadableState
    
    Indicate that the value will be read later.
    This allows an implementation to start an asynchronous prefetch or to include this state in the next batch of reads.
    
    Specified by:
    
    readLater in interface ReadableState<InputT>
    
    Returns:
    
    this for convenient chaining