Package org.apache.flink.streaming.util.keys

Class KeySelectorUtil.ComparableKeySelector<IN>

java.lang.Object

org.apache.flink.streaming.util.keys.KeySelectorUtil.ComparableKeySelector<IN>

Type Parameters:

IN - The type from which the key is extracted.

All Implemented Interfaces:

Serializable, Function, KeySelector<IN,Tuple>, ResultTypeQueryable<Tuple>

Enclosing class:

KeySelectorUtil

public static final class KeySelectorUtil.ComparableKeySelector<IN>
extends Object
implements KeySelector<IN,Tuple>, ResultTypeQueryable<Tuple>

A key selector for selecting key fields via a TypeComparator.

See Also:

Serialized Form

Method Summary

Modifier and Type	Method	Description
Tuple	getKey(IN value)	User-defined function that deterministically extracts the key from an object.
TypeInformation<Tuple>	getProducedType()	Gets the data type (as a TypeInformation) produced by this function or input format.

Methods inherited from class java.lang.Object

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

Method Detail

getKey

public Tuple getKey(IN value)

Description copied from interface: KeySelector

User-defined function that deterministically extracts the key from an object.

For example for a class:

        public class Word {
                String word;
                int count;
        }
 

The key extractor could return the word as a key to group all Word objects by the String they contain.

The code would look like this

        public String getKey(Word w) {
                return w.word;
        }
 

Specified by:

getKey in interface KeySelector<IN,Tuple>

Parameters:

value - The object to get the key from.

Returns:

The extracted key.

getProducedType

public TypeInformation<Tuple> getProducedType()

Description copied from interface: ResultTypeQueryable

Gets the data type (as a TypeInformation) produced by this function or input format.

Specified by:

getProducedType in interface ResultTypeQueryable<IN>

Returns:

The data type produced by this function or input format.