org.apache.flink.api.common.functions

Interface FilterFunction<T>

Type Parameters:

T - The type of the filtered elements.

All Superinterfaces:

Function, Serializable

All Known Implementing Classes:

DropUpdateBeforeFunction, EmptyFieldsCountAccumulator.EmptyFieldFilter, PageRank.EpsilonFilter, RichFilterFunction, SimpleCondition, SubtypeCondition, WebLogAnalysis.FilterByRank, WebLogAnalysis.FilterDocByKeyWords, WebLogAnalysis.FilterVisitsByDate

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@Public
 @FunctionalInterface
public interface FilterFunction<T>
extends Function, Serializable

A filter function is a predicate applied individually to each record. The predicate decides whether to keep the element, or to discard it.

The basic syntax for using a FilterFunction is as follows:

 DataSet<X> input = ...;

 DataSet<X> result = input.filter(new MyFilterFunction());
 

IMPORTANT: The system assumes that the function does not modify the elements on which the predicate is applied. Violating this assumption can lead to incorrect results.

Method Summary

Modifier and Type	Method and Description
boolean	filter(T value) The filter function that evaluates the predicate.

Method Detail

filter

boolean filter(T value)
        throws Exception

The filter function that evaluates the predicate.

IMPORTANT: The system assumes that the function does not modify the elements on which the predicate is applied. Violating this assumption can lead to incorrect results.

Parameters:

value - The value to be filtered.

Returns:

True for values that should be retained, false for values to be filtered out.

Throws:

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