文档介绍：TheScalaAPITheScalaAPIScalahasareputationofbeingadifficultlanguageSomepeoplefeelthatScalaisbeyondwhattheaverageprogrammercanmasterOtherssayit’snomoredifficultthanJavaSomethingshavebeenadded,butalothasbeensimplifiedEveryoneagreesthattheScalaAPIishardertounderstandthantheJavaAPIThiscertainlymakesScalaseemmoredifficultthanitisYoudon’thavetounderstandeverythingaboutamethodinordertouseiteffectivelyThislectureisanattempttode-mystifytheScalaAPI*SearchingTheAPIissearchoriented;everyframehasasearchfieldYoucanclickonaletterandsearchformethods*panionobject*ObjectsAclassisatemplateforcreatingobjectsButifyouneedonlyoneobjectofagiventype,youcanjustcreateitdirectlyobjectInstructor{valname="DavidMatuszek"} Scalaprovidesanumberofpredefinedobjects,suchasConsoleobjectTryIt{ defmain(args:Array[String]):Unit={ valc=Console ("Hello,console!") } }Hello,console!*ClassesAclassisatemplateforcreatingobjects;itmaytakeparametersClassesmaybemarkedascase,abstract,orfinalcaseclasseshavespecialfeaturesTocreateanobject,youmayomitthewordnewCaseclassescanbeusedinpatternmatchingCaseclasseshaveautomaticallygeneratedtoString,hashCode,andequalsmethods(whichusetheconstructorparameters)abstractclassescannotbeinstantiatedfinalclassescannotbesubclassed*CreatingnewobjectsfromclassesWhenyoudefineaclass,youusuallyusethewordnewtocreateobjectsofthatclassobjectTryIt{ defmain(args:Array[String]):Unit={ valt=newThing(1) } } classThing(number:Int){ println(s"I'mThing$number!") }Ifyoumaketheclassacaseclass,youdon’tneedthewordnewobjectTryIt{ defmain(args:Array[String]):Unit={ valt=Thing(1) } } caseclassThing(number:Int){ println(s"I'mThing$number!") }Bothobjectsproducethisoutput:I'mThing1!*CompanionobjectsandclassesIfaclassandanobjecthavethesamenameandaredefinedonthesamesourcefile,esstoallthefeaturesoftheotherobjectThing{ privatevarcount=0 defmain(args:Array[String]):Unit={ newThing(1,2,3) println(s"That's$countThings!") } } classThing(valnumbers:Int*){ for(n<-numbers){ println(s"I'mThing$n!") +=1 } }I