Java期末专项测试卷

Java期末专项测试卷单选题（总共40题）1.单选题Analyzethefollowingcode:()

PublicclassTest{

Publicstaticvoidmain(String[]args){

Int[]x={1,2,3,4};

Int[]y=x;

X=newint[2];

For(inti=0;i<y.length;i++)

System.out.print(y[i]+"");

}

}(1分)A、Theprogramdisplays1234B、Theprogramdisplays00C、Theprogramdisplays0034D、Theprogramdisplays0000答案：A解析：

暂无解析2.单选题Whatistheoutputofthefollowingcode?()

ArrayList<String>list=newArrayList<String>();

Strings1=newString("Java");

Strings2=newString("Java");

List.add(s1);

List.add(s2);

System.out.println((list.get(0)==list.get(1))+""+(list.get(0)).equals(list.get(1)));(1分)A、truefalseB、falsetrueC、truetrueD、falsefalse答案：B解析：

暂无解析3.单选题Thefollowingprogramdisplays__________.()

PublicclassTest{

Publicstaticvoidmain(String[]args){

Strings="Java";

StringBuilderbuffer=newStringBuilder(s);

Change(s);

System.out.println(s);

}

Privatestaticvoidchange(Strings){

S=s+"andHTML";

}

}(1分)A、JavaB、JavaandHTMLC、andHTMLD、nothingisdisplayed答案：A解析：

暂无解析4.单选题Whichofthefollowingcanbeplacedintheblanklineinthefollowingcode?()

PublicclassTest{

Privateintid;

Publicvoidm1(){

_____.id=45;

}

}(1分)A、thisB、Test答案：A解析：

暂无解析5.单选题Analyzethefollowingcode:()

PublicclassTest{

Publicstaticvoidmain(String[]args){

Strings=newString("WelcometoJava");

Objecto=s;

Stringd=(String)o;

}

}(1分)A、WhenassigningstooinObjecto=s,anewobjectiscreated.B、WhencastingotosinStringd=(String)o,anewobjectiscreated.C、WhencastingotosinStringd=(String)o,thecontentsofoischanged.D、s,o,anddreferencethesameStringobject.答案：C解析：

暂无解析6.单选题Assumeanemployeecanworkforonlyonecompany.WhatisthebestsuitablerelationshipbetweenCompanyandEmployee?()(1分)A、NoneB、AggregationC、InheritanceD、Composition答案：D解析：

暂无解析7.单选题Whichistheadvantageofencapsulation?()(1分)A、Onlypublicmethodsareneeded.B、Makingtheclassfinalcausesnoconsequentialchangestoothercode.C、Itchangestheimplementationwithoutchangingaclass'scontractandcausesnoconsequentialchangestoothercode.D、Itchangesaclass'scontractwithoutchangingtheimplementationandcausesnoconsequentialchangestoothercode.答案：C解析：

暂无解析8.单选题Thetimecomplexityforthetheclosestpairofpointsproblemusingdivide-and-conqueris________.()(1分)A、O(n)B、O(nlogn)C、O(logn)D、O(2^n)答案：B解析：

暂无解析9.单选题Analyzethefollowingcodeandchoosethebestanswer:()

PublicclassFoo{

Privateintx;

Publicstaticvoidmain(String[]args){

Foofoo=newFoo();

System.out.println(foo.x);

}

}(1分)A、Sincexisprivate,itcannotbeaccessedfromanobjectfoo.B、

SincexisdefinedintheclassFoo,itcanbeaccessedbyanymethodinsidetheclasswithoutusinganobject.Youcanwritethecodetoaccessxwithoutcreatinganobjectsuchasfoointhiscode.C、

Sincexisaninstancevariable,itcannotbedirectlyusedinsideamainmethod.However,itcanbeaccessedthroughanobjectsuchasfoointhiscode.D、Youcannotcreateaself-referencedobject;thatis,fooiscreatedinsidetheclassFoo.答案：C解析：

暂无解析10.单选题Amethodthatisassociatedwithanindividualobjectiscalled__________.()(1分)A、astaticmethodB、aclassmethodC、aninstancemethodD、anobjectmethod答案：C解析：

暂无解析11.单选题Analyzethefollowingcode.()

Importjava.util.*;

PublicclassTest{

Publicstaticvoidmain(String[]args)throwsException{

TreeSet<String>set=newTreeSet<>();

Set.add("Red");

Set.add("Green");

Set.add("Blue");

System.out.println(set.last());

}

}(1分)A、TheprogramdisplaysRedB、TheprogramdisplaysBlueC、TheprogramdisplaysGreenD、TheprogrammaydisplayRed,Blue,orGreen.E、Theprogramcannotcompile,becausethelast()methodisnotdefinedinSet.答案：A解析：

暂无解析12.单选题Thejava.util.Calendarandjava.util.GregorianCalendarclassesareintroducedinChapter11.Analyzethefollowingcode.Whichofthefollowingstatementsiscorrect?()

1importjava.util.*;

2publicclassTest{

3publicstaticvoidmain(String[]args){

4Calendar[]calendars=newCalendar[10];

5calendars[0]=newCalendar();

6calendars[1]=newGregorianCalendar();

7}

8}(1分)A、TheprogramhasacompileerroronLine4becausejava.util.Calendarisanabstractclass.B、TheprogramhasacompileerroronLine5becausejava.util.Calendarisanabstractclass.C、TheprogramhasacompileerroronLine6becauseCalendar[1]isnotofaGregorianCalendartype.D、Theprogramhasnocompileerrors答案：B解析：

暂无解析13.单选题ThetimecomplexityfortherecursiveFibnaccialgorithminthetextis________.()(1分)A、O(nlogn)B、O(n^2)C、O(logn)D、O(2^n)答案：D解析：

暂无解析14.单选题Thejava.util.Calendarandjava.util.GregorianCalendarclassesareintroducedinChapter11.Analyzethefollowingcode.Whichofthefollowingstatementsiscorrect?()

1importjava.util.*;

2publicclassTest{

3publicstaticvoidmain(String[]args){

4Calendar[]calendars=newCalendar[10];

5calendars[0]=newCalendar();

6calendars[1]=newGregorianCalendar();

7}

8}(1分)A、TheprogramhasacompileerroronLine4becausejava.util.Calendarisanabstractclass.B、TheprogramhasacompileerroronLine5becausejava.util.Calendarisanabstractclass.C、TheprogramhasacompileerroronLine6becauseCalendar[1]isnotofaGregorianCalendartype.D、Theprogramhasnocompileerrors答案：B解析：

暂无解析15.单选题Analyzethefollowingcode.Whichofthefollowingstatementsiscorrect?()

PublicclassTest{

Publicstaticvoidmain(String[]args){

Numberx=newInteger(3);

System.out.println(Value());

System.out.println(pareTo(newInteger(4)));

}

}(1分)A、TheprogramhasacompileerrorbecauseanIntegerinstancecannotbeassignedtoaNumbervariable.B、TheprogramhasacompileerrorbecauseintValueisanabstractmethodinNumber.C、TheprogramhasacompileerrorbecausexdoesnothavethecompareTomethod.D、Theprogramcompilesandrunsfine.答案：C解析：

暂无解析16.单选题Analyzethefollowingcode:()

PublicclassTest{

Publicstaticvoidmain(String[]args){

Doubleradius;

FinaldoublePI=3.15169;

Doublearea=radius*radius*PI;

System.out.println("Areais"+area);

}

}(1分)A、Theprogramhascompileerrorsbecausethevariableradiusisnotinitialized.B、TheprogramhasacompileerrorbecauseaconstantPIisdefinedinsideamethod.C、Theprogramhasnocompileerrorsbutwillgetaruntimeerrorbecauseradiusisnotinitialized.D、Theprogramcompilesandrunsfine.答案：A解析：

暂无解析17.单选题Whenyoupassanarraytoamethod,themethodreceives__________.()(1分)A、acopyofthearrayB、acopyofthefirstelementC、thereferenceofthearrayD、thelengthofthearray答案：C解析：

暂无解析18.单选题Supposelist1isanArrayListandlist2isaLinkedList.Bothcontains1milliondoublevalues.Analyzethefollowingcode:()

A-

For(inti=0;i<list1.size();i++)

Sum+=list1.get(i);

B-

For(inti=0;i<list2.size();i++)

Sum+=list2.get(i);(1分)A、CodefragmentArunsfasterthancodefragmentBB、CodefragmentBrunsfasterthancodefragmentAC、CodefragmentArunsasfastascodefragmentB答案：A解析：

暂无解析19.单选题Analyzethefollowingcode.()

//Program1:

PublicclassTest{

Publicstaticvoidmain(String[]args){

Objecta1=newA();

Objecta2=newA();

System.out.println(a1.equals(a2));

}

}

ClassA{

Intx;

Publicbooleanequals(Aa){

Returnthis.x==a点x;

}

}

//Program2:

PublicclassTest{

Publicstaticvoidmain(String[]args){

Aa1=newA();

Aa2=newA();

System.out.println(a1.equals(a2));

}

}

ClassA{

Intx;

Publicbooleanequals(Aa){

Returnthis.x==a.x;

}

}(1分)A、Program1displaystrueandProgram2displaystrueB、Program1displaysfalseandProgram2displaystrueC、Program1displaystrueandProgram2displaysfalseD、Program1displaysfalseandProgram2displaysfalse答案：B解析：

暂无解析20.单选题Whatistheoutputofthefollowingcode?()

Int[]myList={1,2,3,4,5,6};

For(inti=myList.length-2;i>=0;i--){

MyList[i+1]=myList[i];

}

For(inte:myList)

System.out.print(e+"");(1分)A、123456B、612345C、623451D、112345E、234561答案：D解析：

暂无解析21.单选题Analyzethefollowingcode:()

PublicclassTest{

Publicstaticvoidmain(String[]args){

Int[]x={1,2,3,4,5};

XMethod(x,5);

}

PublicstaticvoidxMethod(int[]x,intlength){

System.out.print(""+x[length-1]);

XMethod(x,length-1);

}

}(1分)A、Theprogramdisplays12346.B、Theprogramdisplays12345andthenraisesanArrayIndexOutOfBoundsException.C、Theprogramdisplays54321.D、Theprogramdisplays54321andthenraisesanArrayIndexOutOfBoundsException.答案：D解析：

暂无解析22.单选题AssumeStringBuilderstrBufis"ABCDEFG",afterinvoking_________,strBufcontains"AEFG".()(1分)A、strBuf.delete(0,3)B、strBuf.delete(1,3)C、strBuf.delete(1,4)D、strBuf.delete(2,4)答案：C解析：

暂无解析23.单选题Youcandeclaretwovariableswiththesamenamein__________.()(1分)A、amethodoneasaformalparameterandtheotherasalocalvariableB、ablockC、twonestedblocksinamethod(twonestedblocksmeansonebeinginsidetheother)D、differentmethodsinaclass答案：D解析：

暂无解析24.单选题Whatistheoutputforthefollowingcode?()

Importjava.util.*;

PublicclassTest{

Publicstaticvoidmain(String[]args){

Set<A>set=newHashSet<>();

Set.add(newA());

Set.add(newA());

Set.add(newA());

Set.add(newA());

System.out.println(set);

}

}

ClassA{

Intr=1;

PublicStringtoString(){

Returnr+"";

}

PublicinthashCode(){

Returnr;

}

}(1分)A、[1]B、[1,1]C、[1,1,1]D、[1,1,1,1]答案：D解析：

暂无解析25.单选题SupposeArrayListxcontainstwostrings[Beijing,Singapore].Whichofthefollowingmethodswillcausethelisttobecome[Beijing,Chicago,Singapore]?()(1分)A、x.add("Chicago")B、x.add(0,"Chicago")C、x.add(1,"Chicago")D、x.add(2,"Chicago")答案：C解析：

暂无解析26.单选题O(1)is________.()(1分)A、constanttimeB、logarithmictimeC、lineartimeD、log-lineartime答案：A解析：

暂无解析27.单选题Theaverage-timecomplexityforheapsortis_________()(1分)A、O(1)B、O(logn)C、O(n)D、O(nlogn)E、O(n*n)答案：D解析：

暂无解析28.单选题Ifyoudeclareanarraydouble[]list={3.4,2.0,3.5,5.5},thehighestindexinarraylistis__________.()(1分)A、0B、1C、2D、3E、4答案：D解析：

暂无解析29.单选题IsArrayList<Number>asubclassofArrayList<?extendsNumber>?()(1分)A、YesB、No答案：A解析：

暂无解析30.单选题Whatisdisplayedbythefollowingcode?()

String[]tokens="A,B;C;D".split("[,;]");

For(inti=0;i<tokens.length;i++)

System.out.print(tokens[i]+"");(1分)A、AB;C;DB、ABCDC、ABC;DD、AB;C;D答案：B解析：

暂无解析31.单选题Supposesets1is[1,2,5]andsets2is[2,3,6].Afters1.removeAll(s2),s1is__________.()(1分)A、[1,2,2,3,5,6]B、[1,2,3,5,6]C、[1,5]D、[2]答案：C解析：

暂无解析32.单选题WhatistheoutputofrunningclassC?()

ClassA{

PublicA(){

System.out.println(

"ThedefaultconstructorofAisinvoked");

}

}

ClassBextendsA{

PublicB(){

System.out.println(

"ThedefaultconstructorofBisinvoked");

}

}

PublicclassC{

Publicstaticvoidmain(String[]args){

Bb=newB();

}

}(1分)A、NothingdisplayedB、"ThedefaultconstructorofBisinvoked"C、"ThedefaultconstructorofAisinvoked"followedby"ThedefaultconstructorofBisinvoked"D、"ThedefaultconstructorofBisinvoked"followedby"ThedefaultconstructorofAisinvoked"E、"ThedefaultconstructorofAisinvoked"答案：C解析：

暂无解析33.TodeclareaninterfacenamedAwithtwogenerictypes,use(1分)A、publicinterfaceA<E>{...}B、publicinterfaceA<E,F>{...}C、publicinterfaceA(E){...}D、publicinterfaceA(E,F){...}答案：B解析：

暂无解析34.单选题The__________algorithmdoesnotcomparekeys.()(1分)A、quicksortB、mergesortC、heapsortD、radixsort答案：D解析：

暂无解析35.单选题AlltheconcreteclassesintheJavaCollectionsFrameworkimplement_____________.()(1分)A、theCloneableinterfaceB、theSerializableinterfacesC、theComparableinterfaceD、theComparatorinterface答案：B解析：

暂无解析36.单选题Youcanuseafor-eachlooptotraverseallelementsinacontainerobjectthatimplements_____.()(1分)A、IteratorB、CollectionC、IterableD、ArrayList答案：C解析：

暂无解析37.单选题Whatistheoutputofthefollowingcode?()

PublicclassTest{

Publicstaticvoidmain(String[]args){

Strings1="WelcometoJava!";

Strings2="WelcometoJava!";

If(s1==s2)

System.out.println("s1ands2referencetothesameStringobject");

Else

System.out.println("s1ands2referencetodifferentStringobjects");

}

}(1分)A、s1ands2referencetothesameStringobjectB、s1ands2referencetodifferentStringobjects答案：A解析：

暂无解析38.单选题Aninputthatresultsintheshortestexecutiontimeiscalledthe_____________.()(1分)A、best-caseinputB、worst-caseinputC、average-caseinput答案：A解析：

暂无解析39.单选题Thekeyword__________isrequiredtodeclareaclass.()(1分)A、publicB、privateC、classD、Alloftheabove.答案：C解析：

暂无解析40.单选题TocreateagenerictypeboundedbyNumber,use()(1分)A、<EextendsNumber>B、<EextendsObject>C、<E>D、<EextendsInteger>答案：A解析：

暂无解析多选题（总共40题）1.多选题__________returnsastring.()(1分)A、String.valueOf(123)B、String.valueOf(12.53)C、String.valueOf(false)D、String.valueOf(newchar[]{'a','b','c'})答案：ABCD解析：

暂无解析2.多选题WhichofthefollowingcanbeusedtoreplaceYYYYYYYYinthefollowingcode?()

PublicclassWildCardDemo3{

Publicstaticvoidmain(String[]args){

GenericStack<String>stack1=newGenericStack<>();

GenericStack<Object>stack2=newGenericStack<>();

Stack2.push("Java");

Stack2.push(2);

Stack1.push("Sun");

Add(stack1,stack2);

WildCardDemo2.print(stack2);

}

Publicstatic<T>voidYYYYYYYY{

While(!stack1.isEmpty())

Stack2.push(stack1.pop());

}

}(1分)A、add(GenericStack<T>stack1,GenericStack<T>stack2)B、add(GenericStack<?extendsT>stack1,GenericStack<T>stack2)C、add(GenericStack<T>stack1,GenericStack<?superT>stack2)D、add(GenericStack<T>stack1,GenericStack<Object>stack2)答案：BC解析：

暂无解析3.多选题Whichofthefollowingstatementsaretrue?()(1分)A、Asubclassisasubsetofasuperclass.B、Asubclassisusuallyextendedtocontainmorefunctionsandmoredetailedinformationthanitssuperclass.C、"classAextendsB"meansAisasubclassofBD、"classAextendsB"meansBisasubclassofA答案：BC解析：

暂无解析4.多选题Thejava.util.Dateclassisintroducedinthissection.Analyzethefollowingcodeandchoosethebestanswer:WhichofthefollowingcodeinIorII,orbothcreatesanobjectoftheDateclass:()

(I)

PublicclassTest{

PublicTest(){

Newjava.util.Date();

}

}

(II)

PublicclassTest{

PublicTest(){

Java.util.Datedate=newjava.util.Date();

}

}(1分)A、IB、IIC、Neither答案：AB解析：

暂无解析5.多选题YoucanusethemethodsintheArraysclassto()(1分)A、findthemaximumobjectinanarraybasedonthecompareTomethod.B、findthemaximumobjectinanarrayusingaComparatorobject.C、sortanarray.D、shuffleanarray.E、doabinarysearchonanarray.答案：CE解析：

暂无解析6.多选题Whichofthefollowingstatementsiscorrect?()(1分)A、Integer.parseInt("12",2);B、Integer.parseInt(100);C、Integer.parseInt("100");D、Integer.parseInt(100,16);E、Integer.parseInt("345",8);答案：CE解析：

暂无解析7.多选题SupposeArrayList<Double>list=newArrayList<>().Whichofthefollowingstatementsarecorrect?()(1分)A、list.add(5.5);//5.5isautomaticallyconvertedtonewDouble(5.5)B、list.add(3.0);//3.0isautomaticallyconvertedtonewDouble(3.0)C、DoubledoubleObject=list.get(0);//NocastingisneededD、doubled=list.get(1);//Automaticallyconvertedtodouble答案：ABCD解析：

暂无解析8.多选题FillinthecodetocompletethefollowingmethodforcomputingaFibonaccinumber.()

Publicstaticlongfib(longindex){

If(index==0)//Basecase

Return0;

Elseif(index==1)//Basecase

Return1;

Else//Reductionandrecursivecalls

Return__________________;

}(1分)A、fib(index-1)B、fib(index-2)C、fib(index-1)+fib(index-2)D、fib(index-2)+fib(index-1)答案：CD解析：

暂无解析9.多选题Whichofthefollowingstatementsiscorrect?()(1分)A、Comparable<String>c=newString("abc");B、Comparable<String>c="abc";C、Comparable<String>c=newDate();D、Comparable<Object>c=newDate();答案：AB解析：

暂无解析10.多选题SupposeArrayListxcontainstwostrings[Beijing,Singapore].Whichofthefollowingmethodwillcausethelisttobecome[Beijing]?()(1分)A、x.remove("Singapore")B、x.remove(0)C、x.remove(1)D、x.remove(2)答案：AC解析：

暂无解析11.Whichofthefollowingstatementsregardingabstractmethodsistrue?()(1分)A、Abstractclasseshaveconstructors.B、Aclassthatcontainsabstractmethodsmustbeabstract.C、Itispossibletodeclareanabstractclassthatcontainsnoabstractmethods.D、Anabstractmethodcannotbecontainedinanonabstractclass.E、Adatafieldcanbedeclaredabstract.答案：ABCD解析：

暂无解析12.多选题Supposes1ands2aretwostrings.Whichofthefollowingstatementsorexpressionsareincorrect?()(1分)A、Strings=newString("newstring");B、Strings3=s1+s2C、s1>=s2D、inti=s1.lengthE、s1.charAt(0)='5'答案：CDE解析：

暂无解析13.多选题Whichofthefollowingstatementsarecorrect?()(1分)A、WhencreatingaRandomobject,youhavetospecifytheseedorusethedefaultseed.B、IftwoRandomobjectshavethesameseed,thesequenceoftherandomnumbersobtainedfromthesetwoobjectsareidentical.C、ThenextInt()methodintheRandomclassreturnsthenextrandomintvalue.D、ThenextDouble()methodintheRandomclassreturnsthenextrandomdoublevalue.答案：ABCD解析：

暂无解析14.多选题Whichofthefollowingstatementsiscorrect?()(1分)A、Integeri=4.5;B、Doublei=4.5;C、Objecti=4.5;D、Numberi=4.5;答案：BCD解析：

暂无解析15.多选题Whichofthefollowingarevalidspecifiersfortheprintfstatement?()(1分)A、%4cB、%10bC、%6dD、%8.2dE、%10.2e答案：ABCE解析：

暂无解析16.多选题InJDK1.5,analyzethefollowingcode.()

Line1:Integer[]intArray={1,2,3};

Line2:inti=intArray[0]+intArray[1];

Line3:intj=i+intArray[2];

Line4:doubled=intArray[0];(1分)A、ItisOKtoassign1,2,3toanarrayofIntegerobjectsinJDK1.5.B、ItisOKtoautomaticallyconvertanIntegerobjecttoanintvalueinLine2.C、ItisOKtomixanintvaluewithanIntegerobjectinanexpressioninLine3.D、Line4isOK.AnintvaluefromintArray[0]objectisassignedtoadoublevariabled点答案：ABCD解析：

暂无解析17.多选题WhichofthefollowingisapossibleoutputfrominvokingMath.random()?()(1分)A、3.43B、0.5C、0.0D、1.0答案：BC解析：

暂无解析18.多选题Whichofthefollowingmethodsareinjava.util.List?()(1分)A、add(intindex,Eelement)B、get(intindex)C、set(intindex,Eelement)D、remove(intindex)E、subList(intfromIndex,inttoIndex)答案：ABCDE解析：

暂无解析19.多选题Analyzethefollowingcode:()

ClassTest{

Privatedoublei;

PublicTest(doublei){

This.t();

This.i=i;

}

PublicTest(){

System.out.println("Defaultconstructor");

This(1);

}

Publicvoidt(){

System.out.println("Invokingt");

}

}(1分)A、this.t()maybereplacedbyt().B、this.imaybereplacedbyi.C、this(1)mustbecalledbeforeSystem.out.println("Defaultconstructor").D、this(1)mustbereplacedbythis(1.0).答案：AC解析：

暂无解析20.多选题Supposeinti=5,whichofthefollowingcanbeusedasanindexforarraydouble[]t=newdouble[100]?()(1分)A、iB、(int)(Math.random()*100))C、i+10D、i+6.5E、Math.random()*100答案：ABC解析：

暂无解析21.多选题Whichofthefollowingstatementsaretrue?()(1分)A、Aheapisacompletebinarytree.B、Eachnodeisgreaterthanorequaltoanyofitschildren.C、Abinarytreeiscompleteifeverylevelofthetreeisfullexceptthatthelastlevelmaynotbefullandalltheleavesonthelastlevelareplacedleft-most.D、Aheapisafullbinarytree.答案：ABC解析：

暂无解析22.多选题WhichofthefollowingcanbeusedtoreplaceYYYYYYYYinthefollowingcode?()

PublicclassWildCardDemo3{

Publicstaticvoidmain(String[]args){

GenericStack<String>stack1=newGenericStack<>();

GenericStack<Object>stack2=newGenericStack<>();

Stack2.push("Java");

Stack2.push(2);

Stack1.push("Sun");

Add(stack1,stack2);

WildCardDemo2.print(stack2);

}

Publicstatic<T>voidYYYYYYYY{

While(!stack1.isEmpty())

Stack2.push(stack1.pop());

}

}(1分)A、add(GenericStack<T>stack1,GenericStack<T>stack2)B、add(GenericStack<?extendsT>stack1,GenericStack<T>stack2)C、add(GenericStack<T>stack1,GenericStack<?superT>stack2)D、add(GenericStack<T>stack1,GenericStack<Object>stack2)答案：BC解析：

暂无解析23.WhichofthefollowingmethodsareintheCollectioninterface?(1分)A、add(o:E)B、addAll(c:Collection<?extendsE>)C、contains(o:Object):booleanD、containsAll(c:Collection<?>):boolean答案：ABCD解析：

暂无解析24.多选题Whichofthefollowingareincorrect?()(1分)A、Anabstractclasscontainsconstructors.B、Theconstructorsinanabstractclassshouldbeprotected.C、Theconstructorsinanabstractclassareprivate.D、Youmaydeclareafinalabstractclass.E、Aninterfacemaycontainconstructors.答案：CDE解析：

暂无解析25.多选题WhatisthepossibleoutputfromSystem.out.println((int)(Math.random()*4))?()(1分)A、0B、1C、2D、3E、4答案：ABCD解析：

暂无解析26.多选题Whatiscorrectaboutapivot?()(1分)A、Apivotdividesalistintotwosublistsofequalsize.B、Apivotcanbechosenarbitrarily.C、Apivotdividesalistintotwosublists,theelementsinthefirstlistarenolargerthanthepivotandtheelementsinthesecondlistarelargerthanthepivot.D、Youshouldalwayschooseapivotthatdividesthelistevenly.答案：BC解析：

暂无解析27.多选题Giventhefollowingcode,findthecompileerror.()

PublicclassTest{

Publicstaticvoidmain(String[]args){

M(newGraduateStudent());

M(newStudent());

M(newPerson());

M(newObject());

}

Publicstaticvoidm(Studentx){

System.out.println(x.toString());

}

}

ClassGraduateStudentextendsStudent{

}

ClassStudentextendsPerson{

@Override

PublicStringtoString(){

Return"Student";

}

}

ClassPersonextendsObject{

@Override

PublicStringtoString(){

Return"Person";

}

}(1分)A、m(newGraduateStudent())causesanerrorB、m(newStudent())causesanerrorC、m(newPerson())causesanerrorD、m(newObject())causesanerror答案：CD解析：

暂无解析28.多选题SupposeArrayList<Double>list=newArrayList<>().Whichofthefollowingstatementsarecorrect?()(1分)A、list.add(5.5);//5.5isautomaticallyconvertedtonewDouble(5.5)B、list.add(3.0);//3.0isautomaticallyconvertedtonewDouble(3.0)C、DoubledoubleObject=list.get(0);//NocastingisneededD、doubled=list.get(1);//Automaticallyconvertedtodouble答案：ABCD解析：

暂无解析29.多选题Whichofthefollowingispoordesign?()(1分)A、Adatafieldisderivedfromotherdatafieldsinthesameclass.B、Amethodmustbeinvokedafter/beforeinvokinganothermethodinthesameclass.C、Amethodisaninstancemethod,butitdoesnotreferenceanyinstancedatafieldsorinvokeinstancemethods