Java核心技術(shù)(高階)-華東師范大學(xué)中國大學(xué)mooc課后章節(jié)答案期末考試題庫2023年

Java核心技術(shù)(高階)_華東師范大學(xué)中國大學(xué)mooc課后章節(jié)答案期末考試題庫2023年Whatistheoutputofthefollowingapplication?packagezoo;publicclassPenguin{privateintvolume=1;privateclassChick{privatestaticintvolume=3;voidchick(){System.out.print("Honk("+Penguin.this.volume+")!");}}publicstaticvoidmain(String...eggs){Penguinpen=newPenguin();finalPenguin.ChicklittleOne=pen.newChick();littleOne.chick();}}

參考答案:

Thecodedoesnotcompile.

Giventheclassdeclarationbelow,whatexpressioncanbeusedtofillintheblanktoreturnthesizevariabledefinedintheBottleclass,printing14atruntime?packagebaby;finalpublicclassBottle{finalprivateintsize=14;finalprotectedclassInsert{privatefinalintsize=25;publicfinalintgetSize(){return____________________;}}finalInsertinsert=newInsert();finalpublicstaticvoidmain(String[]feed){System.out.print(newBottle().insert.getSize());}}

參考答案:

Bottle.this.size

Whichofthefollowingwouldbealegalmodulename?

參考答案:

com.book$

Whichofthefollowingclasstypescannotbemarkedfinalorabstract?

參考答案:

Anonymousinnerclass

給定以下代碼importjava.io.*;classLastError{privateTlastError;publicvoidsetError(Tt){lastError=t;System.out.println("LastError:setError");}}classStrLastErrorextendsLastError{publicStrLastError(Ss){}publicvoidsetError(Ss){System.out.println("StrLastError:setError");}}classTest{publicstaticvoidmain(String[]args){StrLastErrorerr=newStrLastError("Error");err.setError("Lasterror");}}其輸出結(jié)果是

參考答案:

Itresultsinacompilationerror.

Thecodedoesnotcompile,regardlessofwhatisplacedintheblank.packagepresent;interfaceToy{Stringplay();}publicclassGift{publicstaticvoidmain(String[]matrix){abstractclassRobot{}classTransformerextendsRobotimplementsToy{publicStringname="GiantRobot";publicStringplay(){return"DinosaurRobot";}}Transformerprime=newTransformer(){publicStringplay(){returnname;//y1}};System.out.print(prime.play()+""+name);}}

參考答案:

Noneoftheabove

以下代碼publicstatic>intfindFirstGreaterThan(T[]at,Telem){//...}經(jīng)過類型擦除，變成publicstaticintfindFirstGreaterThan(Object[]at,Objectelem){//...}

參考答案:

錯誤

給定以下代碼importjava.util.*;publicclassExtendingGenerics{privatestatic<_____________,U>Uadd(Tlist,Uelement){list.add(element);returnelement;}publicstaticvoidmain(String[]args){Listvalues=newArrayList<>();add(values,"duck");add(values,"duck");add(values,"goose");System.out.println(values);}}以下哪個代碼添加進去，可以使得程序正常編譯。

參考答案:

T

extends

Collection

以下代碼可以編譯通過。publicclassSingleton{publicstaticTgetInstance(){if(instance==null)instance=newSingleton();returninstance;}privatestaticTinstance=null;}

參考答案:

錯誤

給定以下代碼，classShape{/*...*/}classCircleextendsShape{/*...*/}classRectangleextendsShape{/*...*/}classNode{/*...*/}那以下代碼可以編譯通過。Nodenc=newNode<>();Nodens=nc;

參考答案:

錯誤

以下Pair泛型類publicclassPair{publicPair(Kkey,Vvalue){this.key=key;this.value=value;}publicKgetKey();{returnkey;}publicVgetValue();{returnvalue;}publicvoidsetKey(Kkey){this.key=key;}publicvoidsetValue(Vvalue){this.value=value;}privateKkey;privateVvalue;}經(jīng)過類型擦除后，變成以下類publicclassPair{publicPair(Objectkey,Objectvalue){this.key=key;this.value=value;}publicObjectgetKey(){returnkey;}publicObjectgetValue(){returnvalue;}publicvoidsetKey(Objectkey){this.key=key;}publicvoidsetValue(Objectvalue){this.value=value;}privateObjectkey;privateObjectvalue;}

參考答案:

正確

以下代碼能夠編譯通過.publicfinalclassAlgorithm{publicstaticTmax(Tx,Ty){returnx>y?x:y;}}

參考答案:

錯誤

Whichisthefirstlinetocontainacompilererror?1:modulesnake{2:exportscom.snake.tail;3:exportscom.snake.fangstobird;4:requiresskin;5:requirestransitiveskin;6:}

參考答案:

Line5.

SupposeyouhaveastreampipelinewherealltheelementsareoftypeString.Whichofthefollowingcanbepassedtotheintermediateoperationsorted()?

參考答案:

(s,t)->s.length()-t.length()

Fillintheblankssothatbothmethodsproducethesameoutputforallinputs.privatestaticvoidlonger(Optionalopt){if(opt.____________())System.out.println("run:"+opt.get());}privatestaticvoidshorter(Optionalopt){opt.map(x->"run:"+x).____________(System.out::println);}

參考答案:

isPresent,ifPresent

以下代碼能夠編譯通過.publicstaticvoidprint(Listlist){for(Numbern:list)System.out.print(n+"");System.out.println();}

參考答案:

正確

Whatistrueofamodulecontainingafilenamedmodule-info.javawiththefollowingcontents?(Chooseallthatapply.)modulecom.food.supplier{}

參考答案:

Nopackagesinsidethemoduleareautomaticallyexported._Amainmethodinsidethemodulecanberun.

IfthismethodiscalledwithStream.of("hi"),howmanylinesareprinted?publicstaticvoidprint(Streamstream){Consumerprint=System.out::println;stream.peek(print).peek(print).map(s->s).peek(print).forEach(print);}

參考答案:

Four

給定以下代碼，classNodeimplementsComparable{publicintcompareTo(Tobj){/*...*/}//...}那以下代碼可以編譯通過。Nodenode=newNode<>();Comparablecomp=node;

參考答案:

正確

Alocalinnerclasscanaccesswhichtypeoflocalvariables(JDK8+)?I.finalII.privateIII.effectivelyfinal

參考答案:

IandIII

WhatcanbecreatedusingtheJavaPlatformModuleSystemthatcouldnotbecreatedwithoutit?(Chooseallthatapply.)

參考答案:

JMODfile_Smallerruntimeimagesfordistribution

Whatdoesthefollowingoutput?Streamchars=Stream.generate(()->'a');chars.filter(c->c<'b').sorted().findFirst().ifPresent(System.out::print);

參考答案:

Thecodeentersaninfiniteloop.

給定代碼importjava.util.*;classWash{Titem;publicvoidclean(Titems){System.out.println("Cleaned"+items.size()+"items");}}publicclassLaundryTime{publicstaticvoidmain(String[]args){Washwash=new____________wash.clean(Arrays.asList("sock","tie"));}}下列選項哪個可以添加到程序中，并輸出Cleaned2items。

參考答案:

extends,

Wash();

Whatistheoutputofthefollowingapplication?packageworld;publicclassMatrix{privateintlevel=1;classDeep{privateintlevel=2;classDeeper{privateintlevel=5;publicvoidprintReality(){System.out.print(level);System.out.print(""+Matrix.Deep.this.level);System.out.print(""+Deep.this.level);}}}publicstaticvoidmain(String[]bots){Matrix.Deep.Deepersimulation=newMatrix().newDeep().newDeeper();simulation.printReality();}}

參考答案:

522

WhichofthefollowingisanadvantageoftheJavaPlatformModuleSystem?

參考答案:

Encapsulatingpackages

WhatstatementbestdescribesthenotionofeffectivelyfinalinJava?

參考答案:

Alocalvariablethatisnotmarkedfinalbutwhoseprimitivevalueorobjectreferencedoesnotchangeafteritisinitialized.

Whatistheoutputofthefollowingapplication?packagespace;publicclassBottle{publicstaticclassShip{privateenumSail{//w1TALL{protectedintgetHeight(){return100;}},SHORT{protectedintgetHeight(){return2;}};protectedabstractintgetHeight();}publicSailgetSail(){returnSail.TALL;}}publicstaticvoidmain(String[]stars){Bottlebottle=newBottle();Shipq=bottle.newShip();//w2System.out.print(q.getSail());}}

參考答案:

Thecodedoesnotcompilebecauseoflinew2.

Whichofthefollowingcannotincludeastaticmethodinitsdefinition?

參考答案:

Localinnerclass

Whatistheoutputofthefollowingapplication?packageforest;publicclassWoods{staticclassTree{}publicstaticvoidmain(String[]leaves){intwater=10+5;finalclassOakextendsTree{//p1publicintgetWater(){returnwater;//p2}}System.out.print(newOak().getWater());}}

參考答案:

15

Whichstatementistrueofthefollowingmodule?zoo.staff|---zoo|--staff|--Vet.java

參考答案:

Thedirectorystructurewouldbeavalidmoduleifmodule-info.javawereaddeddirectlyunderneathzoo.staff.

Whatistheresultof