Java Reference
In-Depth Information
However,youmightneedadifferentimplementationofoneoftheCollectionsFrame-
work core interfaces. If so, you can extend this framework by implementing the inter-
face,orbysubclassingoneofthemoreconvenient“
Abstract
”classes,suchas
Ab-
stractQueue
.
Youmightrequireacollectionthatisn'tsupportedbytheCollectionsFramework(or
perhaps you only think it isn't supported). For example, you might want to model a
sparsematrix,atablewheremanyormostofitselementsarezeros.Asparsematrixis
a good data structure for implementing a spreadsheet, for example.
Tomodelaspreadsheetorothersparsematrix,youcanworkwithnodes,whichare
objectsconsistingofvalueandlinkfields.Unlikeanarray,whereeachelementstoresa
singlevalueofthesameprimitivetypeorreferencesupertype,anodecanstoremultiple
valuesofdifferenttypes.Itcanalsostorereferencestoothernodes,whichareknownas
links.
Youcanconnectnodestogetherintolinkedlists,but(atleastforsinglylinkedlists)
thereisnoneedtodosobecauseyoucantakeadvantageoftheCollectionsFramework's
LinkedList
class for this task. After all, you should not “reinvent the wheel.”
Broadlyspeaking,theCollectionsFrameworkisanexampleofautilityAPI.
Chapter
6
continues to focus on utility APIs by introducing you to Java's concurrency utilities,
whichextendtheCollectionsFramework,the
java.util.Objects
class,andmore.
