2023年SCJP認證考試題庫

QUESTION61GIVENTHEEXHIBIT:Whichstatementistrue?A.Alloftheassertstatementsareusedappropriately.B.Onlytheassertstatementonline31isusedappropriatelyC.Theassertstatementsonlines29and31areusedappropriatelyD.Theassertstatementsonlines26and29areusedappropriatelyE.Theassertstatementsonlines29and33areusedappropriatelyF.Theassertstatementsonlines29,31and33areusedappropriatelyG.Theassertstatementsonlines26,29and31areusedappropriately斷言應(yīng)當用在“你認為”你的程序不也許產(chǎn)生錯誤的地方，并且有沒有啟用斷言，都不會影響程序的正常運營。斷言使用限制：不要在public方法中，用斷言來檢查參數(shù)的對的性；不要讓斷言語句去解決一些程序必須的流程。因素：1.public方法會被別人調(diào)用，你不能保證他一定啟用斷言；假如沒有啟用，那么用斷言來做參數(shù)的檢查也就沒故意義了。所以不要用斷言來檢查參數(shù)，公共方法的參數(shù)一定要用代碼執(zhí)行檢查； 2.假如用斷言來控制程序執(zhí)行流程，假如沒有啟用斷言，那么程序就不能對的執(zhí)行下去。此外，斷言語句不可以有任何邊界效應(yīng)，不要使用斷言語句去修改變量和改變方法的返回值，假如這樣當啟動斷言和不啟動斷言執(zhí)行的結(jié)果會截然不同。斷言的使用時機：檢查流程的不變性：在if-elseswitch-case的預期結(jié)果之外可以加上斷言做額外的檢查。內(nèi)部執(zhí)行的不變性：if(true){return;}assertfalse;檢查私有方法的參數(shù)，結(jié)果等程序運營中的一致性斷言語句不是永遠會執(zhí)行，可以屏蔽也可以啟用

javac–source1.4*.java需要java–ea啟用assert；當判斷條件為FALSE時就拋犯錯誤。Answer:(C)26行不合適：不要對public方法的參數(shù)斷言29合適：程序員在程序中最不大也許到達的地方斷言

31合適：斷言private方法的參數(shù)

33行不合適：啟用和不啟用斷言會產(chǎn)生不同的程序執(zhí)行序

參考大綱：異常解決—斷言和AssertionErrorQUESTION62GIVENTHEEXHIBIT:Whatistheresult?A. nullB. zeroC. someD. CompilationfailsE. AnexceptionisthrownatruntimeAnswer:(D)13行會報錯，應(yīng)在15行使用elseif參考大綱：流程控制QUESTION63Giventheexhibit:Whatistheresult?A.testB.ExceptionC.CompilationfailsD.NullPointerExceptionAnswer:(C)18行犯錯，應(yīng)當先catch子異常，再catchException；13行把args賦null，14行會報NullPointerException假如沒有第13行運營時14行會報ArrayIndexOutOfBoundsException異常。參考大綱：異常解決QUESTION64Giventheexhibit:Whatistheresult?A.CompilationfailsB.aAaAaAaAAaaAaAC.AAaaAaAaAaaAaAD.AaAAAaaaAaAaAaE.aAaAaAaAaAAAaaF.AnexceptionisthrownatruntimeAnswer:(C)第10行將對strings這個集合做自然排序(ASCII小到大，一個一個比較)Collections.sort(Listlist)對list進行排序，對set不能排序！List里可以放對象，所以當list里面存放的是對象的時候就不能用Collections.sort(Listlist)去排序了。由于JVM不知道用什么規(guī)則去排序??！只有把對象類實現(xiàn)Comparable接口，然后改寫compareTo()參考大綱：集合QUESTION65Giventheexhibit:Whatistheresult?A.0B.1C.2D.3E.4F.Compilationfails.G.AnexceptionisthrownatruntimeAnswer:(D)Set中存放的元素是無序不反復的。假如你想Set里Add一個元素，一方面他會去調(diào)用equals方法，判斷set中是否有該元素，假如有則不更改set的值并返回false，假如沒有，則把元素添加進去，并返回true。Ws1ws2是自定義的類，ws1和ws2equals不相等；String的equals方法已經(jīng)改寫，s1和s2相等；比較兩個對象是否相同,先比較hashcode,假如相同,在用equals方法比較.假如都相同則兩個對象就認為是相同的.Hashcode是把對象的內(nèi)存地址通過運算得來的.基本數(shù)據(jù)類型和基本數(shù)據(jù)類型的包裝類尚有String類都已經(jīng)覆蓋了hashcode(),equals(),所以這些對象的值只要同樣就認為對象同樣.參考大綱：集合QUESTION66Givenapre-genericsimplementationofamethod:Whichthreechangesmustbemadetothemethodsumtousegenerics?(choosethree)A.removeline14B.replaceline14with"inti=iter.next();"C.replaceline13with"for(inti:intList){"D.replaceline13with"for(Iteratoriter:intList)"E.replacethemethoddeclarationwith"sum(List<int>intList)"F.replacethemethoddeclarationwith"sum(List<Integer>intList)"Answer:(A,C,F)publicstaticintsum(List<Integer>intList){intsum=0;for(inti:intList){ sum+=i;}returnsum;}參考大綱：集合和泛型Whatistheresult?A.Compilationfailsduetoanerrorinline23.B.Compilationfailsduetoanerrorinline29.C.AClassCastExceptationoccursinline29.D.AClassCastExceptationoccursinline31.E.Thevalueofallfourobjectprintsinnaturalorder.Answer:(C)Arrays.sort(Object[]a)方法中，a的每一個元素都必須是互相可以比較的（調(diào)用pareTo(Objecto2)）。否則會報ClassCastException的異常。參考大綱：泛型QUESTION68PlacethecodeintopositiontocreateaclassthatmapsfromStringstoIntegervalues.Theresultofexecutionmustbe[one].Someoptionsmaybeusedmorethanonce.Answer:()publicclassNumberNames{ privateHashMap<String,Integer>map=newHashMap<String,Integer>(); publicvoidput(Stringname,Integervalue){ map.put(name,value); } publicSet<String>getNames(){ Returnmap.keySet(); }}QUESTION69Placearesultontoeachmethodcalltoindicatewhatwouldhappenifthemethodcallwereinsertedatline9.Note:Resultscanbeusedmorethanonce.Answer:()MethodResultm1(listA)Compilesandrunswithouterror泛型規(guī)范沒問題m2(listA)Compilesandrunswithouterror泛型規(guī)范沒問題m1(listB)CompilesandrunswithouterrorB是A的子類，泛型規(guī)范沒問題m2(listB)Doesnotcompilem1(listO)Doesnotcompilem2(listO)DoesnotcompileQUESTION70Giventheexhibit:Whatistheresult?A.apple:appleB.carrot:appleC.apple:bananaD.banana:appleE.carrot:carrotF.carrot:bananaAnswer:(C)PriorityQueue優(yōu)先級隊列：預設(shè)是自然排序，因此pq內(nèi)的元素順序?qū)⑹莂pple->banana->carrotpoll()取第一個元素，取完之后刪除，peek取第一個元素，并不刪除元素QUESTION71Given:AprogrammerisdevelopingaclassKey,thatwillbeusedasakeyinastandardjava.util.HashMap.Whichtwomethodsshouldbeoverriddentoassurethatkeyworkscorrectlyasakey?(choosetwo)A.publicinthashCode()B.publicBooleanequals(Keyk)C.publicintcompareTo(Objecto)D.publicBooleanequals(Objecto)Answer:(A,D)HashMap中的key不能反復，因此必須實現(xiàn)hashCode和equals方法QUESTION72---Giventheexhibit:Whichtwo,insertedatline2willallowthecodetocompile?(ChooseTwo)A.publicclassMinMax<?>{B.publicclassMinMax<?extendsNumber>{C.publicclassMinMax<NextendsObject>{D.publicclassMinMax<NextendsNumber>{E.publicclassMinMax<?extendsObject>{F.publicclassMinMax<NextendsInteger>{Answer:(D,F)N是泛型類別變量，它相稱于一個類型。A 類聲明是不能用？這個萬用字符。B 同上C Object沒有doubleValue()方法。D OK.E 同A。F OK.QUESTION73Giventheexhibit:enumExample{ONE,TWO,THREE}Whichstatementistrue?A.Theexpressions(ONE==ONE)andONE.equals(ONE)arebothguaranteedtobetrue.B.Theexpression(ONE<TWO)isguaranteedtobetrueandONE.compareTo(TWO)isguaranteedtobelessthanone.C.TheExamplevaluescannotbeusedinarawjava.util.HashMap.;instead,theprogrammermustuseajava.util.EnumMap.D.TheExamplevaluescanbeusedinajava.util.SortedSet,butthesetwillNOTbesortedbecauseenumeratedTypedoNOTIMPLEMENTjava.lang.Comparable.Answer:(A)A對的B不能保證C錯誤枚舉類型的元素是可以用在HASHMAP里的HashMap<Integer,Example>h=newHashMap<Integer,Example>;h.put(1,Example.ONE);D錯誤，枚舉類型的元素值是可以放入SortedSet里的例如TreeSet.把枚舉類型的元素轉(zhuǎn)成字符串在放入其中，字符串就已經(jīng)實現(xiàn)comparable接口?？梢宰匀慌判?。SortedSet<Example>s=newTreeSet<Example>();s.add(Example.TWO);s.add(Example.ONE);System.out.println(s);打印出結(jié)果[ONE,TWO]QUESTION74Giventheexhibit:WhichlineofcodemarkstheearliestpointthatanobjectreferencedbyintObjbecomesacandidateforgarbagecollection?A.Line16B.Line17C.Line18D.Line19E.TheobjectisNOTacandidateforgarbagecollection.Answer:(D)intObj一直會被numbers引用，直到19行之后QUESTION75Given:Andthecommandlineinvocation:javaYippee2abcWhatistheresult?A.abB.bcC.abcD.Compilationfails.E.Anexceptionisthrownatruntime.Answer:(B)QUESTION76Aclassgames.cards.PokeriscorrectlydefinedinthejarfilePoker.jar.AuserwantstoexecutethemainmethodofPokeronaUNIXsystemusingthecommand:Javagames.cards.PokerWhatallowstheusertodothis?A.putPoker.jarindirectory/stuff/java,andsettheCLASSPATHtoinclude/stuff/javaB.putPoker.jarindirectory/stuff/java,andsettheCLASSPATHtoinclude/stuff/java/*.jarC.putPoker.jarindirectory/stuff/java,andsettheCLASSPATHtoinclude/stuff/java/Poker.jarD.putPoker.jarindirectory/stuff/java/games/cards,andsettheCLASSPATHtoinclude/stuff/javaE.putPoker.jarindirectory/stuff/java/games/cards,andsettheCLASSPATHtoinclude/stuff/java/*.jarF.putPoker.jarindirectory/stuff/java/games/cards,andsettheCLASSPATHtoinclude/stuff/java/Poker.jarAnswer:(C)classpath中須明確寫明poker.jar，不能用*.jarQUESTION77Whichthreecodefragments,addedindividuallyatline29,producetheoutput100?(Choosethree.)A.n=100;B.i.setX(100);C.o.getY().setX(100);D.i=newInner();i.setX(100);E.0.setY(i);i=newInner();i.setX(100);F.i=newInner();i.setX(100);o.setY(i);Answer:(B,C,F)根據(jù)內(nèi)存關(guān)系可知QUESTION78GivenaclassRepetition:AndgivenanotherclassDemo:Whichcodeshouldbeinsertedatline1ofDemo.javatocompileandrunDemotoprint"pizzapizza"A.importutils.*;B.staticimportutils.*;C.importutils.Repetition.*;D.staticimportutils.Repetition.*;E.importutils.Repetition.twice();F.importstaticutils.Repetition.twice;G.staticimportutils.Repetition.twice;Answer:(F)靜態(tài)import引入靜態(tài)方法.importstaticutils..Repetition*;或者importstaticutils.Repetition.twice;A 正常的導入類,Demo的第5行要new實例才干帶用twice方法.B staticimport順序顛倒,并且要加上class名C 正常的導入,類名后面不能跟*D 順序顛倒E 正常的導入,只能導入包下的類,不能導入類里的方法.G 順序顛倒QUESTION79Given:Andtheinvocation:Whatistheresult?A.Anexceptionisthrownatruntime.B."Stringisempty"isprintedtooutput.C.Compilationfailsbecauseofanerrorinline12.D."Stringisnotempty"isprintedtooutput.Answer:(A)A空指針異常------------------“|”是非短路邏輯運算符QUESTION80Exhibit:Giventhefully-qualifiedclassnames:com.foo.bar.Dogcom.foo.bar.blatz.Bookcom.bar.Carcom.bar.blatz.SunWhichgraphrepresentsthecorrectdirectorystructureforaJARfilefromwhichthoseclassescanbeusedbythecompilerandJVM?A.JarAB.JarBC.JarCD.JarDE.JarEAnswer:(A)QUESTION81Given:andtwoseparatecommandlineinvocations:javaYippeejavaYippee1234Whatistheresult?Nooutputisproduced.123B. Nooutputisproduced.234C. Nooutputisproduced.1234D. Anexceptionisthrownatruntime.123E. Anexceptionisthrownatruntime.234F. Anexceptionisthrownatruntime.1234Answer:(B)QUESTION82Given:Whatistheresult?A.CompilationfailsB.AnexceptionisthrownatruntimeC.doStuffx=6mainx=6D.doStuffx=5mainx=5E.doStuffx=5mainx=6F.doStuffx=6mainx=5Answer:(D)第10行參數(shù)x是值傳遞，不會改變main中x的值。QUESTION83Given:WhenthedoSomethingmethodiscalled,afterwhichlinedoestheObjectcreatedinline5becomeavailableforgarbagecollection?A.Line5B.Line6C.Line7D.Line8E.Line9F.Line10Answer:(D)棧內(nèi)存用來存放基本類型的變量和對象的引用變量(對象的地址)堆內(nèi)存用來存放由new創(chuàng)建的對象和數(shù)組QUESTION84Given:Whatistheresult?A. ExceptionB. A,B,ExceptionC. Compilationfailsbecauseofanerrorinline20.D. Compilationfailsbecauseofanerrorinline14.E. ANullPointerExceptionisthrownatruntime.Answer:(D)改寫的規(guī)定,子類拋出的異常要比父類的異常要小.本題中父類沒有異常,子類也不能有異常.QUESTION85Given:Whatistheresult?A.harrierB.shepherdC.retrieverD.CompilationfailsE.retrieverharrierF.Anexceptionisthrownatruntime.Answer:(D)18行，casedefault:語法錯誤，應(yīng)改成default:QUESTION86Given:Whatistheresult?A. A,B,CB. B,C,AC. CompilationfailsD. ThecoderunswithnooutputE. AnexceptionisthrownatruntimeAnswer:(B)LinkedList有順序性，QUESTION87GivenWhatistheresult?A.endB.CompilationfailsC.exceptionendD.exceptiontestendE.AThrowableisthrownbymainF.AnExceptionisthrownbymainAnswer:(E)16行拋出Error,沒有捕獲。Throwable，Error和Exception都是他的子類QUESTION88Given:Whichthree,willmakecodeon37executeA.Theinstancegetsgarbagecollected.B.Thecodeonline33throwsanexception.C.Thecodeonline35throwsanexception.D.Thecodeonline31throwsanexception.E.Thecodeonline33executessuccessfully.Answer:(B,C,E)QUESTION89Given:Whatistheresult?A.CompilationfailsB.piisbiggerthan3.C.Anexceptionoccursatruntime.D.piisbiggerthan3.Haveaniceday.E.piisnotbiggerthan3.Haveaniceday.Answer:(A)18行finally是配合try使用的.QUESTION90Given:Whichcode,insertedatline16willcauseajava.lang.ClassCastException?A.Alphaa=x;B.Foof=(Delta)x;C.Foof=(Alpha)x;D.Betab=(Beta)(Alpha)x;Answer:(B)轉(zhuǎn)到子類別拋異常。.QUESTION91Givenamethodthatmustensurethatitsparameterisnotnull:What,insertedatline12,istheappropriatewaytohandleanullvalue?A.assertvalue==null;B.assertvalue!=null,"valueisnull";C.if(value==null){thrownewAssertionException("valueisnull");}D.if(value==null){thrownewIllegalArgumentException("valueisnull");}Answer:(D)A 不要用斷言對公共方法的參數(shù)進行判斷B 同上C 沒有AssertionException這個類;AssertionError繼承自Error，handleerror是沒故意義的D OK拋出參數(shù)錯誤的異常.QUESTION92PlacethecorrectCodeintheCodeSampletoachievetheexpectedresults.Expectedresults:Output:12481632CodeSampleAnswer:()for(intx:y){QUESTION93Given:WhichtwowillproduceanAssertionError?(Choosetwo.)A.javatestB.java-eatestC.javatestfile1D.java-eatestfile1E.java-eatestfile1file2F.java–ea:testtestfile1Answer:(B,E)QUESTION94Given:WhichstatementistrueifaResourceExceptionisthrownonline86?A.Line92willnotexecute.B.Theconnectionwillnotberetrievedinline85.C.Theresourceconnectionwillnotbeclosedonline88. D.Theenclosingmethodwillthrowanexceptiontoitscaller.Answer:(C)QUESTION95AssumingthattheserializeBanana()andthedeserializeBanana()methodswillcorrectlyuseJavaserializationandgiven:Whatistheresult?A.restore400B.restore403C.restore453D.Compilationfails.E.Anexceptionisthrownatruntime.Answer:(C)QUESTION96Given:Whatistheresult?A.CompilationfailsB.Piisapproximately3.C.Piisapproximately3.141593.D.Anexceptionisthrownatruntime.Answer:(D)%d打印一個整數(shù)，規(guī)定接受一個整數(shù)拋IllegalFormatConversionExceptionQUESTION97Given:Whatistheresult?A.intLongB.ShortLongC.CompilationfailsD.Anexceptionisthrownatruntime.Answer:(A)QUESTION98Chaintheseconstructorstocreateobjectstoreadfromafilenamed"in"andtowritetoafilenamed"out".Answer:()newBufferedReader(newFileReader(“in”));newPrintWriter(newBufferedWriter(newFileWriter(“out”)));QUESTION99PlacethecodefragmentsintopositiontouseaBufferedReadertoreadinanentiretextfile.Answer:()classPrintFile{ publicstaticvoidmain(String[]args){ BufferedReaderbuffReader=null; //morecodeheretoinitializebuffReader try{ Stringtemp; while((temp=buffReader.readLine())!=null){ System.out.println(temp); } }catch(IOExceptione){ e.printStackTrace(); } }}QUESTION100Giventhismethodinaclass:Whichstatementistrue?A.ThiscodeisNOTthread-safe.B.TheprogrammercanreplaceStringBufferwithStringBuilderwithnootherchanges.C.Thiscodewillperformpoorly.Forbetterperformance,thecodeshouldberewritten:return"<"++">";D.ThiscodewillperformwellandconvertingthecodetouseStringBuilderwillnotenhancetheperformance.Answer:(B)QUESTION101Given:WhatcreatestheappropriateDateFormatobjectandaddsadaytotheDateobject?A. 35.Dateformatdf=Dateformat.getDateFormat();42.d.setTime((60*60*24)+d.getTime());B. 35.Dateformatdf=Dateformat.getDateInstance();42.d.setTime((1000*60*60*24)+d.getTime());C. 35.Dateformatdf=Dateformat.getDateFormat();42.d.setLocalTime((1000*60*60*24)+d.getLocalTime());D. 35.Dateformatdf=Dateformat.getDateInstance();42.d.setLocalTime((60*60*24)+d.getLocalTime());Answer:(B)轉(zhuǎn)換成求加1天以后改日期的毫秒數(shù)，再調(diào)用setTime()設(shè)立時間QUESTION102Given:WhichtwostatementsaretrueabouttheresultifthelocaleisLocale.US?(Choosetwo.)A.Thevalueofbis2.B.Thevalueofais3.14.C.Thevalueofbis2.00.D.Thevalueofais3.141.E.Thevalueofais3.1415.F.Thevalueofais3.1416.G.Thevalueofbis2.0000.Answer:(C,F)QUESTION103Placethecorrectdescriptionofthecompileroutputonthecodefragmenttobeinsertedatline4and5.Thesamecompileroutputmaybeusedmorethanonce.Answer:()QUESTION104Given:Whichthreewillcompilesuccessfully?(Choosethree.)A.Objecto=Old.get0(newLinkedList());B.Objecto=Old.get0(newLinkedList<?>());C.Strings=Old.get0(newLinkedList<String>());D.Objecto=Old.get0(newLinkedList<Object>());E.Strings=(String)Old.get0(newLinkedList<String>());Answer:(A,D,E)B錯誤<?>不應(yīng)出現(xiàn)在這里C錯誤get0()方法的回傳值是Object,因此不可賦值給StringQUESTION105Exhibit:Whichstatementistrueaboutthesetvariableonline12?A.Thesetvariablecontainsallsixelementsfromthecollcollection,andtheorderisguaranteedtobepreserved.B.Thesetvariablecontainsonlythreeelementsfromthecollcollection,andtheorderisguaranteedtobepreserved.C.Thesetvariablecontainsallsixelementsfromthecollcollection,buttheorderisNOTguaranteedtobepreserved.D.Thesetvariablecontainsonlythreeelementsfromthecollcollection,buttheorderisNOTguaranteedtobepreserved.Answer:(D)Set中元素是不能反復，沒有順序的QUESTION106Given:WhatistheappropriateddefinitionofthehashCodemethodinclassPerson?A.returnsuper.hashCode();B.returnname.hashCode()+age*7;C.returnname.hashCode()+comment.hashCode()/2;D.returnname.hashCode()+comment.hashCode()/2-age*3;Answer:(B)兩個equals的對象，hashCode()應(yīng)當相等，equals中是判斷age和name相等，所以hashCode也用age和name計算，A,C,D也許導致兩個相等的對象，hashCode不相等QUESTION107Given:Whichstatementistrue?A.TheequalsmethoddoesNOTproperlyoverridetheObject.equalsmethod.B.Compilationfailsbecausetheprivateattributecannotbeaccessedinline5.C.Toworkcorrectlywithhash-baseddatastructures,thisclassmustalsoimplementthehashCodemethod.D.WhenaddingPersonobjectstojava.util.Setcollection,theequalsmethodinline4willpreventduplicates.Answer:(A)QUESTION108Given:Whichcode,insertedatline4,guaranteesthatthisprogramwilloutput[1,2]?A.Setset=newTreeSet();B.Setset=newHashSet();C.Setset=newSortedSet();D.Listset=newSortedList();E.Setset=newLinkedHashSet();Answer:(A)TreeSet可自動排序，SortedSet是接口，不能實例化QUESTION109Given:What,insertedatline39,willsortthekeysinthepropsHashMap?A.Array.sort(s);B.s=newTreeSet(s);C.Collections.sort(s);D.s=newSortedSet(s);Answer:(B)QUESTION110Placecodeintotheclasssothatitcompilesandgeneratestheoutputanswer=42.Note:Codeoptionsmaybeusedmorethanonce.Answer:()publicclassGen<T>{ privateTobject; publicGen(Tobject){ this.object=object;}publicTgetObject(){ returnobject;}…}QUESTION111----------------???第一選項解釋Given:PlacetheCompilationResultsoneachcodestatementtoindicatewhetherornotthatcodewillcompileifinsertedintothetakeList()method.Answer:()List<String>StrList=newArrayList<String>();List<Integer>IntList=newArrayList<Integer>();List<?extendsObject>list;//該類型的泛型之能接受對象賦值,不能直接對該對象進行add操作.//list.add(newObject());list=StrList;list=IntList;QUESTION112WhichtwocodefragmentswillexecutethemethoddoStuff()inaseparatethread?(Choosetwo.)A. newThread(){publicvoidrun(){doStuff();}};B. newThread(){publicvoidstart(){doStuff();}};C. newThread(){publicvoidstart(){doStuff();}}.run();D. newThread(){publicvoidrun(){doStuff();}}.start();E. newThread(newrunnable(){publicvoidrun(){doStuff();}}).run();F. newThread(newrunnable(){publicvoidrun(){doStuff();}}).start();Answer:(D,F)D匿名類別中復寫run方法，并調(diào)用start()方法啟動線程F運用匿名實現(xiàn)runnable接口中的run方法，并調(diào)用start()啟動線程QUESTION113Given:Whichtocanberesults?(Choosetwo.)A. java.lang.RuntimeException:ProblemB. run.java.lang.RuntimeException:ProblemC. Endofmethod.java.lang.RuntimeException:ProblemD. Endofmethod.run.java.lang.RuntimeException:ProblemE. run.java.lang.RuntimeException:ProblemEndofmethodAnswer:(D、E)在t中拋出RuntimeException，不干擾主線程的執(zhí)行；QUESTION114----Given:Whichthreechangesshouldbemadetoadaptthisclasstobeusedsafelybymultiplethreads?(Choosethree.)A.declarereset()usingthesynchronizedkeywordB.declaregetName()usingthesynchronizedkeywordC.declaregetCount()usingthesynchronizedkeywordD.declaretheconstructorusingthesynchronizedkeywordE.declareincrement()usingthesynchronizedkeywordAnswer:(A,C,E)D選項錯誤，由于構(gòu)造方法不能用synchronized修飾name是final變量不會有多線程上維護的問題QUESTION115Given:Whichstatementistrue?A.CompilationfailsB.Anexceptionisthrownatruntime.C.Synchronizingtherun()methodwouldmaketheclassthread-safe.D.Thedatainvariable"x"areprotectedfromconcurrentaccessproblems.E.DeclaringthedoThings()methodasstaticwouldmaketheclassthread-safe.F.WrappingthestatementswithindoThings()i