java介绍外文翻译

外文原文IntroductiontoJavaautor：MartinNgobye.source：ComputingStaticSliceforJavaProgramsJavaisdesignedtomeetthechallengesofapplicationdevelopmentinthecontextofheterogeneous,network-widedistributedenvironments.Paramountamongthesechallengesissecuredeliveryofapplicationsthatconsumetheminimumofsystemresources,canrunonanyhardwareandsoftwareplatform,andcanbeextendeddynamically.Javaoriginatedaspartofaresearchprojecttodevelopadvancedsoftwareforawidevarietyofnetworkdevicesandembeddedsystems.Thegoalwastodevelopasmall,reliable,portable,distributed,real-timeoperatingplatform.Whentheprojectstarted,C++wasthelanguageofchoice.ButovertimethedifficultiesencounteredwithC++grewtothepointwheretheproblemscouldbestbeaddressedbycreatinganentirelynewlanguageplatform.DesignandarchitecturedecisionsdrewfromavarietyoflanguagessuchasEiffel,SmallTalk,ObjectiveC,andCedar/Mesa.Theresultisalanguageplatformthathasprovenidealfordevelopingsecure,distributed,networkbasedend-userapplicationsinenvironmentsrangingfromnetwork-embeddeddevicestotheWorld-WideWebandthedesktop.ThedesignrequirementsofJavaaredrivenbythenatureofthecomputingenvironmentsinwhichsoftwaremustbedeployed.ThemassivegrowthoftheInternetandtheWorld-WideWebleadsustoacompletelynewwayoflookingatdevelopmentanddistributionofsoftware.Toliveintheworldofelectroniccommerceanddistribution,Javamustenablethedevelopmentofsecure,highperformance,andhighlyrobustapplicationsonmultipleplatformsinheterogeneous,distributednetworks.Operatingonmultipleplatformsinheterogeneousnetworksinvalidatesthetraditionalschemesofbinarydistribution,release,upgrade,patch,andsoon.Tosurviveinthisjungle,Javamustbearchitectureneutral,portable,anddynamicallyadaptable.TheJavasystemthatemergedtomeettheseneedsissimple,soitcanbeeasilyprogrammedbymostdevelopers;familiar,sothatcurrentdeveloperscaneasilylearnJava;objectoriented,totakeadvantageofmodernsoftwaredevelopmentmethodologiesandtofitintodistributedclient-serverapplications;multithreaded,forhighperformanceinapplicationsthatneedtoperformmultipleconcurrentactivities,suchasmultimedia;andinterpreted,formaximumportabilityanddynamiccapabilities.Together,theaboverequirementscomprisequiteacollectionofbuzzwords,solet’sexaminesomeofthemandtheirrespectivebenefitsbeforegoingon.What’scompletelynewisthemannerinwhichJavaanditsrun-timesystemhavecombinedthemtoproduceaflexibleandpowerfulprogrammingsystem..DevelopingyourapplicationsusingJavaresultsinsoftwarethatisportableacrossmultiplemachinearchitectures,operatingsystems,andgraphicaluserinterfaces,secure,andhighperformance,WithJava,yourjobasasoftwaredeveloperismucheasier—youfocusyourfullattentionontheendgoalofshippinginnovativeproductsontime,basedonthesolidfoundationofJava.Thebetterwaytodevelopsoftwareishere,now,broughttoyoubytheJavalanguageplatform.VerydynamiclanguageslikeLisp,TCL,andSmallTalkareoftenusedforprototyping.Oneofthereasonsfortheirsuccessatthisisthattheyareveryrobust—youdon’thavetoworryaboutfreeingorcorruptingmemory.Similarly,programmerscanberelativelyfearlessaboutdealingwithmemorywhenprogramminginJava,Thegarbagecollectionsystemmakestheprogrammer’sjobvastlyeasier;withtheburdenofmemorymanagementtakenofftheprogrammer’sshoulders,storageallocationerrorsgoaway.AnotherreasoncommonlygiventhatlanguageslikeLisp,TCL,andSmallTalkaregoodforprototypingisthattheydon’trequireyoutopindowndecisionsearlyon—theselanguagesaresemanticallyrich.Javahasexactlytheoppositeproperty:itforcesyoutomakeexplicitchoices.Alongwiththesechoicescomealotofassistance—youcanwritemethodinvocationsand,ifyougetsomethingwrong,yougettoldaboutitatcompiletime.Youdon’thavetoworryaboutmethodinvocationerror.TheJavabeginnermustgrasp30basicconceptsBasicconcept1.InOOPtheonlyrelationsiswhattheobject’sinterface,suchasthecomputersellerheleavesaloneinternalstructureofelectricalsource,butheisonlyconcernedaboutthatwhetherthepowerwillbesuppliedtoyou,alsosolongasknowcanornotbutisnothowandwhy.Allproceduresaremakeupofcertainattributeandthebehaviorobject,thedifferentobjectvisitinvokesthroughthefunctioninvocation,betweentheobjectallintercommunionareinvokethroughthemethodinvocation,Byobjectdataencapsulation,enhancesreuserateverymuch..2.InOOPthemostimportantthoughtisclass,theclassisthetemplate,isablueprint,constructanobjectfromaclass,namelyconstructaninstanceoftheclass.3.Encapsulation:isthatcombinesthedataandthebehaviorinapackage)andhidesthedatatherealizationprocesstotheobjectuser,inanobjectdataiscalleditsinstancefield.4.Throughexpandsaclasstoobtainanewclassiscalledinheritance,butallclassesareconstructedbytheobjectsuperrootclassofexpansion,superrootclassofasfollowscanmaketheintroduction.5.Object3principalcharacteristicsBehavior---explainedthisobjectcanmakewhat.Tate---whentheobjectexertsthemethodobjectreflection.Dentity---andothersimilarbehaviorobjectsdiscriminationsymbols.Eachobjecthasonlyindentityandamongthreecharacteristicstheyaffectmutually.6.Relationsamongclasses:Use-a:DependentrelationHas-a:PolymerizationrelationIs-a:inheritorrelation--example:AclasshasinheritedBclass,thistimeAclassnotonlyhasBclas