com.tangosol.util
Interface MapIndex

public interface MapIndex

MapIndex is used to correlate values stored in an indexed Map (or attributes of those values) to the corresponding keys in the indexed Map.

Author:

cp/gg 2002.10.31

Method Summary

Object	get(Object oKey) Using the index information if possible, get the value associated with the specified key.
Map	getIndexContents() Get the Map that contains the index contents.
ValueExtractor	getValueExtractor() Obtain the ValueExtractor object that the MapIndex uses to extract an indexable Object from a value stored in the indexed Map.
boolean	isOrdered() Determine if the MapIndex orders the contents of the indexed information.

Method Detail

getValueExtractor

ValueExtractor getValueExtractor()

Obtain the ValueExtractor object that the MapIndex uses to extract an indexable Object from a value stored in the indexed Map. This property is never null.

Returns:

a ValueExtractor object, never null

isOrdered

boolean isOrdered()

Determine if the MapIndex orders the contents of the indexed information. To determine in which way the contents are ordered, get the Comparator from the index contents SortedMap object.

Returns:

true if the index contents are ordered, false otherwise

getIndexContents

Map getIndexContents()

Get the Map that contains the index contents.

The keys of the Map are the return values from the ValueExtractor operating against the indexed Map's values, and for each key, the corresponding value stored in the Map is a Set of keys to the indexed Map.

If the MapIndex is known to be ordered, then the returned Map object will be an instance of SortedMap. The SortedMap may or may not have a Comparator object associated with it; see SortedMap.comparator().

A client should assume that the returned Map object is read-only and must not attempt to modify it.

Returns:

a Map (or a SortedMap) of the index contents

get

Object get(Object oKey)

Using the index information if possible, get the value associated with the specified key. This is expected to be more efficient than using the ValueExtractor against an object containing the value, because the index should already have the necessary information at hand.

Parameters:

oKey - the key that specifies the object to extract the value from

Returns:

the value that would be extracted by this MapIndex's ValueExtractor from the object specified by the passed key