上海德邦物流股份有限公司招聘java面試真題

上海德邦物流股份有限公司招聘java面試真題一、選擇題(20)［含多選］。(請(qǐng)?jiān)谡_的答案上打”V”)Question1)Whichofthefollowingstatementsaretrue?AninterfacecanonlycontainmethodandnotvariablesInterfacescannothaveconstructorsAclassmayextendonlyoneotherclassandimplementonlyoneinterfaceInterfacesaretheJavaapproachtoaddressingitslackofmultipleinheritance,butrequireimplementingclassestocreatethefunctionalityoftheInterfaces.Question2)Whichofthefollowingstatementsaretrue?ThegarbagecollectionalgorithminJavaisvendorimplementedThesizeofprimitivesisplatformdependentThedefaulttypeforanumericalliteralwithdecimalcomponentisafloatYoucanmodifythevalueinanInstanceoftheIntegerclasswiththesetValuemethodQuestion3)Whichofthefollowingaretruestatements?I/OinJavacanonlybeperformedusingtheListenerclassesTheRandomAccessFileclassallowsyoutomovedirectlytoanypointafileThecreationofanamedinstanceoftheFileclasscreatesamatchingfileintheunderlyingoperatingsystemonlywhentheclosemethodiscalled.ThecharacteristicsofaninstanceoftheFileclasssuchasthedirectoryseparator,dependonthecurrentunderlyingoperatingsystemQuestion4)WhatwillhappenwhenyouattempttocompileandrunthefollowingcodeclassBase{publicvoidBase(){System.out.println(“Base”);}}publicclassInextendsBase{publicstaticvoidmain(Stringargv[]){Ini=newIn();}}CompiletimeerrorBaseisakeywordCompilationandnooutputatruntimeOutputofBaseRuntimeerrorBasehasnovalidconstructorQuestion5)Youhaveapublicclasscalledmyclasswiththemainmethoddefinedasfollowspublicstaticvoidmain(Stringparm[]){System.out.println(parm[0]);}IfyouattempttocompiletheclassandruntheprogramasfollowsjavamyclasshelloWhatwillhappen?Compiletimeerror,mainisnotcorrectlydefinedRuntimeerror,mainisnotcorrectlydefinedCompilationandoutputofjavaCompilationandoutputofhelloQuestion6)WhichofthefollowingstatementsareNOTtrue?Ifaclasshasanyabstractmethodsitmustbedeclaredabstractitself.Whenappliedtoaclass,thefinalmodifiermeansitcannotbesub-classedAllmethodsinanabstractclassmustbedeclaredasabstracttransientandvolatileareJavamodifiersQuestion7)Whatwillhappenwhenyouattempttocompileandrunthefollowingclass?classBase{Base(inti){System.out.println(“Base”);}}classSevernextendsBase{publicstaticvoidmain(Stringargv[]){Severns=newSevern();}voidSevern(){System.out.println(“Severn”);}Compilationandoutputofthestring”Severn”atruntimeCompilationandnooutputatruntimeCompiletimeerrorCompilationandoutputofthestring”Base”Question8)Whichofthefollowingstatementsaretrue?StaticmethodscannotbeoverridentobenonstaticStaticmethodscannotbedeclaredasprivatePrivatemethodscannotbeoverloadedAnoverloadedmethodcannotthrowexceptionsnotcheckedinthebaseclassQuestion9)Whichofthefollowingstatementsaretrue?TheautomaticgarbagecollectionoftheJVMpreventsprogramsfromeverrunningoutofmemoryAprogramcansuggestthatgarbagecollectionbeperformedbutnotforceitGarbagecollectionisplatformindependentAnobjectbecomeseligibleforgarbagecollectionwhenallreferencesdenotingitaresettonull.Question10)GiventhefollowingcodepublicclassSytch{intx=2000;publicstaticvoidmain(Stringargv[]){System.out.println(“Ms”+argv[1]+”P(pán)leasepay$”+x);WhatwillhappenifyouattempttocompileandrunthiscodewiththecommandlinejavaSytchJonesDiggleCompilationandoutputofMsDigglePleasepay$2000CompiletimeerrorCompilationandoutputofMsJonesPleasepay$2000CompilationbutruntimeerrorQuestion11)Youneedtoreadinthelinesofalargetextfilecontainingtensofmegabytesofdata.WhichofthefollowingwouldbemostsuitableforreadinginsuchafilenewFileInputStream(“”)newInputStreamReader(newFileInputStream(“”))newBufferedReader(newInputStreamReader(newFileInputStream(“”)));newRandomAccessFileraf=newRandomAccessFile(“myfile.txt”,”+rw”);Question12)Whichofthefollowingstatementsaretrue?1)Constructorscannothaveavisibilitymodifier2)Constructorsarenotinherited3)Constructorscanonlyhaveaprimitivereturntype4)Constructorscanbemarkedpublicandprotected,butnotprivateQuestion13)Whichstatementistrue?Ananonymousinnerclassmaybedeclaredasfinal.Ananonymousinnerclasscanbedeclaredasprivate.Ananonymousinnerclasscanimplementmultipleinterfaces.Ananonymousinnerclasscanaccessfinalvariablesinanyenclosingscope.Constructionofaninstanceofastaticinnerclassrequiresaninstanceoftheenclosingouterclass.Question14)publicclassFoo{publicstaticvoidmain(Stringsgf[]){StringBuffera=newStringBuffer(“A”);StringBufferb=newStringBuffer(“B”);operate(a,b);System.out.println(a+”,”+b);}staticvoidoperate(StringBufferx,StringBuffery){x.append(y);y=x;}}Whatistheresult?1)Thecodecompilesandprints“A.B”.2)Thecodecompilesandprints“A.A”.3)Thecodecompilesandprints“B.B”.4)Thecodecompilesandprints“AB.B”.5)Thecodecompilesandprints“AB.AB”.Question15)Whichofthefollowingthreadstatetransitionsarevalid?Fromreadytorunning.Fromrunningtoready.Fromrunningtowaiting.Fromwaitingtorunning.Fromwaitingtoready.Fromreadytowaiting.Question16)Whatistheresultofattemptingtocompileandrunthefollowingprogram?publicclassTest{privateinti=j;privateintj=10;publicstaticvoidmain(Stringargs[]){System.out.println((newTest()).i);}}TeCompilererrorcomplainingaboutaccessrestrictionofprivatevariablesofTest.Compilererrorcomplainingaboutforwardreferencing.Noerror-Theoutputis0;Noerror-Theoutputis10;Question17)Whichtwocannotdirectlycauseathreadtostopexecuting?exitingfromasynchronizedblockcallingthewaitmethodonanobjectcallingthenotifymethodonanobjectcallingareadmethodonanInputStreamobjectcallingthesetPrioritymethodonathreadobjectQuestion18)Whichofthefollowingarecorrect,ifyoucompilethefollowingcode?publicclassCloseWindowextendsFrameimplementsWindowListener{publicCloseWindow(){addWindowListener(this);//ThisislistenerregistrationsetSize(300,300);setVisible(true);}publicvoidwindowClosing(WindowEvente){System.exit(0);}publicstaticvoidmain(Stringargs[]){CloseWindowCW=newCloseWindow();}}CompiletimeerrorRuntimeerrorCodecompilesbutFramesdoesnotlistentoWindowEventsCompileandrunssuccessfullyQuestion19)Whichstatementsdescribeguaranteedbehaviorofthegarbagecollectionandfinalizationmechanisms?1）Objectsaredeletedwhentheycannolongerbeaccessedthroughanyreference.2）Thefinalize（）methodwilleventuallybecalledoneveryobject.3）Thefinalize（）methodwillneverbecalledmorethanonceonanobject.4）Anobjectwillnotbegarbagecollectedaslongasitispossibleforanactivepartoftheprogramtoaccessitthroughareference.5）Thegarbagecollectorwilluseamarkandsweepalgorithm.Question20）Aclassdesignrequiresthatamembervariableshouldbeaccessibleonlybysamepackage,whichmodiferwordshouldbeused?1）protected2）public3）nomodifer4）private二．簡(jiǎn)答題。（80）（請(qǐng)注意字跡填寫(xiě)工整）說(shuō)明SQL語(yǔ)言中的Select中的Having子句作用。（5）解釋UnionAll與Union的區(qū)別。（5）現(xiàn)有關(guān)系數(shù)據(jù)庫(kù)如下（20）用SQL語(yǔ)言實(shí)現(xiàn)以下四小題。1、檢索沒(méi)有獲得獎(jiǎng)學(xué)金、同時(shí)至少有一門(mén)課程成績(jī)?cè)?5分以上的學(xué)生信息，包括學(xué)號(hào)、姓名、專(zhuān)業(yè)。（5）2、檢索沒(méi)有任何一門(mén)課程成績(jī)?cè)?0分以下的所有學(xué)生信息，包括學(xué)號(hào)、姓名、專(zhuān)業(yè)。（5）3、對(duì)成績(jī)得過(guò)滿分（100分）的學(xué)生，如果沒(méi)有獲得獎(jiǎng)學(xué)金的，將其獎(jiǎng)學(xué)金設(shè)為1000元。（5）4、定義學(xué)生成績(jī)得過(guò)滿分（100分）的課程視圖vwAAA，包括課程號(hào)、名稱和學(xué)分。（5）2.5用java實(shí)現(xiàn)快速排序算法。（