org.apache.flink.api.common.functions

Class RichReduceFunction<T>

java.lang.Object

org.apache.flink.api.common.functions.AbstractRichFunction

org.apache.flink.api.common.functions.RichReduceFunction<T>

Type Parameters:

T - Type of the elements that this function processes.

All Implemented Interfaces:

Serializable, Function, ReduceFunction<T>, RichFunction

@Public
public abstract class RichReduceFunction<T>
extends AbstractRichFunction
implements ReduceFunction<T>

Rich variant of the ReduceFunction. As a RichFunction, it gives access to the RuntimeContext and provides setup and teardown methods: RichFunction.open(org.apache.flink.configuration.Configuration) and RichFunction.close().

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
RichReduceFunction()

Method Summary

Modifier and Type	Method and Description
abstract T	reduce(T value1, T value2) The core method of ReduceFunction, combining two values into one value of the same type.

Methods inherited from class org.apache.flink.api.common.functions.AbstractRichFunction

close, getIterationRuntimeContext, getRuntimeContext, open, setRuntimeContext

Methods inherited from class java.lang.Object

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

Constructor Detail

RichReduceFunction

public RichReduceFunction()

Method Detail

reduce

public abstract T reduce(T value1,
                         T value2)
                  throws Exception

Description copied from interface: ReduceFunction

The core method of ReduceFunction, combining two values into one value of the same type. The reduce function is consecutively applied to all values of a group until only a single value remains.

Specified by:

reduce in interface ReduceFunction<T>

Parameters:

value1 - The first value to combine.

value2 - The second value to combine.

Returns:

The combined value of both input values.

Throws:

Exception - This method may throw exceptions. Throwing an exception will cause the operation to fail and may trigger recovery.