org.apache.flink.examples.java.relational

Class EmptyFieldsCountAccumulator.EmptyFieldFilter

java.lang.Object

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

org.apache.flink.api.common.functions.RichFilterFunction<EmptyFieldsCountAccumulator.StringTriple>

org.apache.flink.examples.java.relational.EmptyFieldsCountAccumulator.EmptyFieldFilter

All Implemented Interfaces:

Serializable, FilterFunction<EmptyFieldsCountAccumulator.StringTriple>, Function, RichFunction

Enclosing class:

EmptyFieldsCountAccumulator

public static final class EmptyFieldsCountAccumulator.EmptyFieldFilter
extends RichFilterFunction<EmptyFieldsCountAccumulator.StringTriple>

This function filters all incoming tuples that have one or more empty fields. In doing so, it also counts the number of empty fields per attribute with an accumulator (registered under EmptyFieldsCountAccumulator.EMPTY_FIELD_ACCUMULATOR).

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
EmptyFieldFilter()

Method Summary

Modifier and Type	Method and Description
boolean	filter(EmptyFieldsCountAccumulator.StringTriple t) The filter function that evaluates the predicate.
void	open(OpenContext openContext) Initialization method for the function.

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

EmptyFieldFilter

public EmptyFieldFilter()

Method Detail

open

public void open(OpenContext openContext)
          throws Exception

Description copied from interface: RichFunction

Initialization method for the function. It is called before the actual working methods (like map or join) and thus suitable for one time setup work. For functions that are part of an iteration, this method will be invoked at the beginning of each iteration superstep.

The openContext object passed to the function can be used for configuration and initialization. The openContext contains some necessary information that were configured on the function in the program composition.

 public class MyFilter extends RichFilterFunction<String> {

     private String searchString;

     public void open(OpenContext openContext) {
         // initialize the value of searchString
     }

     public boolean filter(String value) {
         return value.equals(searchString);
     }
 }
 

By default, this method does nothing.

1. If you implement open(OpenContext openContext), the open(OpenContext openContext) will be invoked and the open(Configuration parameters) won't be invoked. 2. If you don't implement open(OpenContext openContext), the open(Configuration parameters) will be invoked in the default implementation of the open(OpenContext openContext).

Parameters:

openContext - The context containing information about the context in which the function is opened.

Throws:

Exception - Implementations may forward exceptions, which are caught by the runtime. When the runtime catches an exception, it aborts the task and lets the fail-over logic decide whether to retry the task execution.

filter

public boolean filter(EmptyFieldsCountAccumulator.StringTriple t)

Description copied from interface: FilterFunction

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.

Specified by:

filter in interface FilterFunction<EmptyFieldsCountAccumulator.StringTriple>

Specified by:

filter in class RichFilterFunction<EmptyFieldsCountAccumulator.StringTriple>

Parameters:

t - The value to be filtered.

Returns:

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