org.bluedb.api.index

Interface KeyExtractor<K extends ValueKey,V extends java.io.Serializable>

Type Parameters:

K - the key type of the index or the type of data that the collection is being indexed on. It must be a concretion of ValueKey (UUIDKey, StringKey, LongKey, or IntegerKey).

V - the value type of the collection being indexed

All Superinterfaces:

java.io.Serializable

All Known Subinterfaces:

IntegerIndexKeyExtractor<V>, LongIndexKeyExtractor<V>, StringIndexKeyExtractor<V>, UUIDIndexKeyExtractor<V>

public interface KeyExtractor<K extends ValueKey,V extends java.io.Serializable>
extends java.io.Serializable

This is used by the BlueIndex class to extract data in the form of index keys from each value in the BlueCollection. The value can then be quickly found using those index keys.

The following sub types are more simple and can be used in place of this: IntegerIndexKeyExtractor, LongIndexKeyExtractor, StringIndexKeyExtractor, UUIDIndexKeyExtractor. Note that key extractors are serialized by BlueIndex and for this reason it is NOT recommended to use lambdas or anonymous inner classes to define key extractors.

Method Summary

Modifier and Type	Method and Description
java.util.List<K>	extractKeys(V value) Extracts data from the given value in the form of index keys.
java.lang.Class<K>	getType()

Method Detail

extractKeys

java.util.List<K> extractKeys(V value)

Extracts data from the given value in the form of index keys. The BlueIndex class uses this method to map the resulting index keys to this value.

Parameters:

value - the value from which index keys are to be extracted

Returns:

one or many index keys representing the data that this value should be indexed on

getType

java.lang.Class<K> getType()

Returns:

the index key type class