Java期末练习测试卷

Java期末练习测试卷单选题（总共40题）1.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2.单选题FillinthemostappropriatecodeintheblanksintheMyIntclass?()

PublicclassMyIntimplements_______{

Intid;

PublicMyInt(intid){

This.id=id;

}

PublicStringtoString(){

ReturnString.valueOf(id);

}

PublicintcompareTo(_______arg0){

If(id>arg0.id)

Return1;

Elseif(id<arg0.id)

Return-1;

Else

Return0;

}

}(1分)A、Comparable/ObjectB、Comparable<MyInt>/MyIntC、Comparable<MyInt>/ObjectD、Comparable/MyInt答案：B解析：

暂无解析3.TodeclareaninterfacenamedAwithagenerictype,use(1分)A、publicinterfaceA<E>{...}B、publicinterfaceA<E,F>{...}C、publicinterfaceA(E){...}D、publicinterfaceA(E,F){...}答案：A解析：

暂无解析4.单选题Analyzethefollowingcode.()

ClassTest{

Publicstaticvoidmain(String[]args){

StringBuilderstrBuf=newStringBuilder(4);

StrBuf.append("ABCDE");

System.out.println("What'sstrBuf.charAt(5)?"+strBuf.charAt(5));

}

}(1分)A、TheprogramhasacompileerrorbecauseyoucannotspecifyinitialcapacityintheStringBuilderconstructor.B、Theprogramhasaruntimeerrorbecausebecausethebuffer'scapacityis4,butfivecharacters"ABCDE"areappendedintothebuffer.C、Theprogramhasaruntimeerrorbecausethelengthofthestringinthebufferis5after"ABCDE"isappendedintothebuffer.Therefore,strBuf.charAt(5)isoutofrange.)D、Theprogramcompilesandrunsfine.)答案：C解析：

暂无解析5.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6.单选题Supposeaheapisstoredinanarraylistasfollows:{100,55,92,23,33,81}.Afterinserting103,whatisthecontentofthearraylist?()(1分)A、{100,55,92,23,33,81,103}B、{100,55,103,23,33,92,81}C、{103,55,92,23,33,81,92}D、{103,55,100,23,33,81,92}E、{103,55,92,23,33,81,100}答案：D解析：

暂无解析7.单选题Whichofthefollowingstatementsisfalse?()(1分)A、Apublicclasscanbeaccessedbyaclassfromadifferentpackage.B、Aprivatemethodcannotbeaccessedbyaclassinadifferentpackage.C、Aprotectedmethodcanbeaccessedbyasubclassinadifferentpackage.D、Amethodwithnovisibilitymodifiercanbeaccessedbyaclassinadifferentpackage.答案：D解析：

暂无解析8.单选题Whatmodifiershouldyouuseonaclasssothataclassinthesamepackagecanaccessitbutaclass(includingasubclass)inadifferentpackagecannotaccessit?()(1分)A、publicB、privateC、protectedD、Usethedefaultmodifier.答案：D解析：

暂无解析9.单选题TheGrahamalgorithmforfindingaconvexhulltakes______________time.()(1分)A、O(n)B、O(nlogn)C、O(logn)D、O(n^2)答案：B解析：

暂无解析10.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11.单选题FillinthecodeinComparable______c=newDate();()(1分)A、<String>B、<?>C、<Date>D、<E>答案：C解析：

暂无解析12.单选题Showtheoutputofthefollowingcode()

PublicclassTest1{

Publicstaticvoidmain(String[]args){

System.out.println(f2(2,0));

}

Publicstaticintf2(intn,intresult){

If(n==0)

Return0;

Else

Returnf2(n-1,n+result);

}

}(1分)A、0B、1C、2D、3答案：A解析：

暂无解析13.单选题Ifyouwanttostorenon-duplicatedobjectsintheorderinwhichtheyareinserted,youshoulduse____________.()(1分)A、HashSetB、LinkedHashSetC、TreeSetD、ArrayListE、LinkedList答案：B解析：

暂无解析14.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15.单选题Theoutputofthefollowingcodeis____________.()

LinkedHashSet<String>set1=newLinkedHashSet<>();

Set1.add("NewYork");

LinkedHashSet<String>set2=(LinkedHashSet<String>)(set1.clone());

Set1.add("Atlanta");

Set2.add("Dallas");

System.out.println(set2);(1分)A、[NewYork]B、[NewYork,Atlanta]C、[NewYork,Atlanta,Dallas]D、[NewYork,Dallas]答案：D解析：

暂无解析16.单选题Whatistheoutputofthefollowingcode?()

Importjava.util.*;

PublicclassTest{

Publicstaticvoidmain(String[]args){

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

List.add(newStudent("Peter",65));

List.add(newStudent("Jill",50));

List.add(newStudent("Sarah",34));

Collections.sort(list);

System.out.print(list+"");

Collections.sort(list,newStudentComparator1());

System.out.println(list);

}

StaticclassStudentComparator1implementsComparator<Student>{

Publicintcompare(Students1,Students2){

ReturnpareTo();

}

}

StaticclassStudentimplementsComparable<Student>{

Stringname;

Intage;

Student(Stringname,intage){

T=name;

This.age=age;

}

PublicintcompareTo(Students){

Returnthis.age-s.age;

}

PublicStringtoString(){

Return"["+name+","+age+"]";

}

}

}(1分)A、[[Sarah,34],[Jill,50],[Peter,65]][[Sarah,34],[Jill,50],[Peter,65]]B、[[Jill,50],[Peter,65],[Sarah,34]][[Jill,50],[Peter,65],[Sarah,34]]C、[[Sarah,34],[Jill,50],[Peter,65]][[Jill,50],[Peter,65],[Sarah,34]]D、[[Jill,50],[Peter,65],[Sarah,34]][[Sarah,34],[Jill,50],[Peter,65]]答案：C解析：

暂无解析17.单选题Whatistheoutputofthefollowingcode?()

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

List.add(1);

List.add(2);

List.add(3);

List.remove(2);

System.out.println(list);(1分)A、[1,2,3]B、[1,2]C、[1]D、[1,3]E、[2,3]答案：B解析：

暂无解析18.单选题Whichdatatypeshouldyouuseifyouwanttostoreduplicateelementsandbeabletoinsertordeleteelementsanywhereefficiently?()(1分)A、ArrayListB、LinkedListC、VectorD、SetE、Stack答案：B解析：

暂无解析19.单选题Whatisdisplayedbythefollowingstatement?()

System.out.println("Javaisneat".replaceAll("is","AAA"));(1分)A、JavaAAAneatB、JavaAAAneatC、JavaAAAneatD、JavaAAAneat答案：C解析：

暂无解析20.单选题Showtheoutputofthefollowingcode:()

PublicclassTest{

Publicstaticvoidmain(String[]args){

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

Increase(x);

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

Increase(y[0]);

System.out.println(x[0]+""+y[0]);

}

Publicstaticvoidincrease(int[]x){

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

X[i]++;

}

Publicstaticvoidincrease(inty){

Y++;

}

}(1分)A、00B、11C、22D、21E、12答案：D解析：

暂无解析21.单选题Analyzethefollowingcode.()

1publicclassTest{

2publicstaticvoidmain(String[]args){

3Fruit[]fruits={newFruit(2),newFruit(3),newFruit(1)};

4java.util.Arrays.sort(fruits);

5}

6}

ClassFruit{

Privatedoubleweight;

PublicFruit(doubleweight){

This.weight=weight;

}

}(1分)A、TheprogramhasacompileerrorbecausetheFruitclassdoesnothaveano-argconstructor.B、TheprogramhasaruntimeerroronLine3becausetheFruitclassdoesnothaveano-argconstructor.C、TheprogramhasacompileerroronLine4becausetheFruitclassdoesnotimplementthejava.lang.ComparableinterfaceandtheFruitobjectsarenotcomparable.D、TheprogramhasaruntimeerroronLine4becausetheFruitclassdoesnotimplementthejava.lang.ComparableinterfaceandtheFruitobjectsarenotcomparable.答案：D解析：

暂无解析22.单选题WhatistheoutputofrunningclassTest?()

PublicclassTest{

Publicstaticvoidmain(String[]args){

NewCircle9();

}

}

PublicabstractclassGeometricObject{

ProtectedGeometricObject(){

System.out.print("A");

}

ProtectedGeometricObject(Stringcolor,booleanfilled){

System.out.print("B");

}

}

PublicclassCircle9extendsGeometricObject{

/**No-argconstructor*/

PublicCircle9(){

This(1.0);

System.out.print("C");

}

/**Constructcirclewithaspecifiedradius*/

PublicCircle9(doubleradius){

This(radius,"white",false);

System.out.print("D");

}

/**Constructacirclewithspecifiedradius,filled,andcolor*/

PublicCircle9(doubleradius,Stringcolor,booleanfilled){

Super(color,filled);

System.out.print("E");

}

}(1分)A、ABCDB、BACDC、CBAED、AEDCE、BEDC答案：E解析：

暂无解析23.AssumeCalendarcalendar=newGregorianCalendar().__________returnsthemonthoftheyear.()(1分)A、calendar.get(Calendar.MONTH);B、calendar.get(Calendar.MONTH_OF_YEAR);C、calendar.get(Calendar.WEEK_OF_MONTH);D、calendar.get(Calendar.WEEK_OF_YEAR);答案：A解析：

暂无解析24.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25.单选题Supposeyouwishtoprovideanaccessormethodforabooleanpropertyfinished,whatsignatureofthemethodshouldbe?()(1分)A、publicvoidgetFinished()B、publicbooleangetFinished()C、publicbooleanisFinished()D、publicvoidisFinished()答案：C解析：

暂无解析26.单选题Tofindamaximumobjectinanarrayofstrings()g点,String[]names={"red","green","blue"}),use(D)(1分)A、Arrays.max(names)B、Arrays.sort(names)C、Collections.max(names)D、Collections.max(Arrays.asList(names))E、Noneoftheabove答案：E解析：

暂无解析27.单选题ThetimecomplexityfortheTowersofHonoialgorithminthetextis________.()(1分)A、O(n)B、O(n^2)C、O(n^3)D、O(2^n)答案：D解析：

暂无解析28.单选题WhichofthefollowingdatatypesdoesnotimplementtheCollectioninterface?()(1分)A、HashSetB、TreeSetC、ArrayListD、LinkedListE、Map答案：E解析：

暂无解析29.单选题Giventworeferencevariablest1andt2,ift1.equals(t2)istrue,t1==t2___________.()(1分)A、isalwaystrueB、isalwaysfalseC、maybetrueorfalse答案：C解析：

暂无解析30.单选题Analyzethefollowingcode.()

//Program1:

PublicclassTest{

Publicstaticvoidmain(String[]args){

Objecta1=newA();

Objecta2=newA();

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

}

}

ClassA{

Intx;

Publicbooleanequals(Objecta){

Returnthis.x==((A)a).x;

}

}

//Program2:

PublicclassTest{

Publicstaticvoidmain(String[]args){

Objecta1=newA();

Objecta2=newA();

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

}

}

ClassA{

Intx;

Publicbooleanequals(Aa){

Returnthis.x==a点x;

}

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

暂无解析31.单选题WhatisthereturnvalueforxMethod(4)aftercallingthefollowingmethod?()

StaticintxMethod(intn){

If(n==1)

Return1;

Else

Returnn+xMethod(n-1);

}(1分)A、12B、11C、10D、9答案：C解析：

暂无解析32.单选题Fillinthecodetocompletethefollowingmethodforcheckingwhetherastringisapalindrome.()

PublicstaticbooleanisPalindrome(Strings){

ReturnisPalindrome(s,0,s.length()-1);

}

PublicstaticbooleanisPalindrome(Strings,intlow,inthigh){

If(high<=low)//Basecase

Returntrue;

Elseif(s.charAt(low)!=s.charAt(high))//Basecase

Returnfalse;

Else

Return_______________________________;

}(1分)A、isPalindrome(s)B、isPalindrome(s,low,high)C、isPalindrome(s,low+1,high)D、isPalindrome(s,low,high-1)E、isPalindrome(s,low+1,high-1)答案：E解析：

暂无解析33.单选题FillinthecodeinComparable______c=newDate();()(1分)A、<String>B、<?>C、<Date>D、<E>答案：A解析：

暂无解析34.单选题Theiterator()methodisdefinedinthe__________interface.()(1分)A、IteratorB、CollectionC、IterableD、ArrayList答案：C解析：

暂无解析35.单选题_______isnotareferencetype.()(1分)A、AclasstypeB、AninterfacetypeC、AnarraytypeD、Aprimitivetype答案：D解析：

暂无解析36.单选题FillinthemostappropriatecodeintheblanksintheMyIntclass?()

PublicclassMyIntimplements_______{

Intid;

PublicMyInt(intid){

This.id=id;

}

PublicStringtoString(){

ReturnString.valueOf(id);

}

PublicintcompareTo(_______arg0){

If(id>arg0.id)

Return1;

Elseif(id<arg0.id)

Return-1;

Else

Return0;

}

}(1分)A、Comparable/ObjectB、Comparable<MyInt>/MyIntC、Comparable<MyInt>/ObjectD、Comparable/MyInt答案：B解析：

暂无解析37.单选题GiventhedeclarationCirclex=newCircle(),whichofthefollowingstatementismostaccurate.()(1分)A、xcontainsanintvalue.B、xcontainsanobjectoftheCircletype.C、xcontainsareferencetoaCircleobject.D、Youcanassignanintvaluetox.答案：C解析：

暂无解析38.单选题ThetimecomplexityfortheEuclidalgorithmis________.()(1分)A、O(n)B、O(n^2)C、O(logn)D、O(2^n)答案：C解析：

暂无解析39.单选题Whatarethebasecasesinthefollowingrecursivemethod?()

PublicstaticvoidxMethod(intn){

If(n>0){

System.out.print(n%10);

XMethod(n/10);

}

}(1分)A、n>0B、n<=0C、nobasecasesD、n<0答案：B解析：

暂无解析40.单选题Usingthepartitionalgorithmtopartitionanarray{5,8,10,3,4,19,2}foraquicksort,whatistheresultingarrayafterthepartition?()(1分)A、{5,8,10,3,4,19,2}B、{2,3,4,5,8,10,19}C、{2,3,4,5,10,19,8}D、{3,2,4,5,10,19,8}E、{3,2,4,5,8,10,19}答案：D解析：

暂无解析多选题（总共40题）1.多选题Toobtainthedistancebetweenthepoints(40,50)and(5.5,4.4),use_________.()(1分)A、distance(40,50,5.5,4.4)B、newPoint2D(40,50).distance(5.5,4.4)C、newPoint2D(40,50).distance(newPoint2D(5.5,4.4))D、newPoint2D(5.5,4.4).distance(40,50)E、newPoint2D(5.5,4.4).distance(newPoint2D(40,50))答案：BCDE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__________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4.多选题Whatiscorrectaboutapivot?()(1分)A、Apivotdividesalistintotwosublistsofequalsize.B、Apivotcanbechosenarbitrarily.C、Apivotdividesalistintotwosublists,theelementsinthefirstlistarenolargerthanthepivotandtheelementsinthesecondlistarelargerthanthepivot.D、Youshouldalwayschooseapivotthatdividesthelistevenly.答案：BC解析：

暂无解析5.多选题WhichofthefollowingarecorrectmethodsinMap?()(1分)A、containsKey(Objectkey)B、containsValue(Objectvalue)C、remove(Objectkey)D、remove(intindex)E、isEmpty()答案：ABCE解析：

暂无解析6.多选题Howcanyouinitializeanarrayoftwocharactersto'a'and'b'?()(1分)A、char[]charArray=newchar[2];charArray={'a','b'};B、char[2]charArray={'a','b'};C、char[]charArray={'a','b'};D、char[]charArray=newchar[]{'a','b'};答案：CD解析：

暂无解析7.多选题Whichofthefollowingstatementsaretrue?()(1分)A、TheStringclassimplementsComparable.B、TheDateclassimplementsComparable.C、TheDoubleclassimplementsComparable.D、TheBigIntegerclassimplementsComparable.答案：ABCD解析：

暂无解析8.多选题Whichofthefollowingstatementsistrue?()(1分)A、Youcanalwayspassaninstanceofasubclasstoaparameterofitssuperclasstype.Thisfeatureisknownaspolymorphism.B、Thecompilerfindsamatchingmethodaccordingtoparametertype,numberofparameters,andorderoftheparametersatcompiletime.C、Amethodmaybeimplementedinseveralsubclasses.TheJavaVirtualMachinedynamicallybindstheimplementationofthemethodatruntime.D、Dynamicbindingcanapplytostaticmethods.E、Dynamicbindingcanapplytoinstancemethods.答案：ABCE解析：

暂无解析9.多选题Whichofthefollowingstatementsaretrue?()(1分)A、Aclassshoulddescribeasingleentityandalltheclassoperationsshouldlogicallyfittogethertosupportacoherentpurpose.B、Aclassshouldalwayscontainano-argconstructor.C、Theconstructorsmustalwaysbepublic.D、Theconstructorsmaybeprotected.答案：AD解析：

暂无解析10.多选题Analyzethefollowingcode:()

PublicclassTestextendsA{

Publicstaticvoidmain(String[]args){

Testt=newTest();

T.print();

}

}

ClassA{

Strings;

A(Strings){

This.s=s;

}

Publicvoidprint(){

System.out.println(s);

}

}(1分)A、TheprogramdoesnotcompilebecauseTestdoesnothaveadefaultconstructorTest().B、TheprogramhasanimplicitdefaultconstructorTest(),butitcannotbecompiled,becauseitssuperclassdoesnothaveadefaultconstructor.TheprogramwouldcompileiftheconstructorintheclassAwereremoved.C、TheprogramwouldcompileifadefaultconstructorA(){}isaddedtoclassAexplicitly.D、Theprogramcompiles,butithasaruntimeerrorduetotheconflictonthemethodnameprint.答案：BC解析：

暂无解析11.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12.多选题Whichofthefollowingstatementsaretrue?()(1分)A、Everyrecursivemethodmusthaveabasecaseorastoppingcondition.B、Everyrecursivecallreducestheoriginalproblem,bringingitincreasinglyclosertoabasecaseuntilitbecomesthatcase.C、Infiniterecursioncanoccurifrecursiondoesnotreducetheprobleminamannerthatallowsittoeventuallyconvergeintothebasecase.D、Everyrecursivemethodmusthaveareturnvalue.E、Arecursivemethodisinvokeddifferentlyfromanon-recursivemethod.答案：ABC解析：

暂无解析13.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14.多选题Theelementsin________aresorted.()(1分)A、TreeSetB、ListC、TreeMapD、HashSetE、LinkedHashSet答案：AC解析：

暂无解析15.多选题TheRationalclassinthischapterisdefinedasasubclassofjava.lang.Number.Whichofthefollowingexpressionsiscorrect?()(1分)A、Rational.doubleValue();B、Rational.doubleValue("5/4");C、newRational(5,4).doubleValue();D、newRational(5,4).toDoubleValue();E、newRational(5,4).intValue();答案：CE解析：

暂无解析16.多选题SupposeArrayListxcontainstwostrings[Beijing,Singapore].Whichofthefollowingmethodwillcauseruntimeerrors?()(1分)A、x.get(1)B、x.set(2,"NewYork");C、x.get(2)D、x.remove(2)E、x.size()答案：BCD解析：

暂无解析17.多选题WhichofthefollowingcomplexityisO(nlogn)?()(1分)A、300n+400n*nB、23nlogn+50C、45n+45nlogn+503D、n*n*n+nlogn答案：BC解析：

暂无解析18.多选题Whichofthefollowingstatementsiscorrect?()(1分)A、Genericscanhelpdetecttypeerrorsatcompiletime,thusmakeprogramsmorerobust.B、Genericscanmakeprogramseasytoread.C、Genericscanavoidcumbersomecastings.D、Genericscanmakeprogramsrunfaster.答案：ABC解析：

暂无解析19.多选题Whichofthefollowingstatementsarecorrect?()(1分)A、newJava.math.BigInteger("343");B、newjava.math.BigDecimal("343.445");C、newjava.math.BigInteger(343);D、newjava.math.BigDecimal(343.445);答案：AB解析：

暂无解析20.多选题Whichofthefollowingstatementsconvertadoublevaluedintoastrings?()(1分)A、s=(newDouble(d)).toString();B、s=d;C、s=newDouble(d).stringOf();D、s=String.stringOf(d);E、s=d+"";答案：AE解析：

暂无解析21.多选题Whichofthefollowingaretrue?()(1分)A、Youcaninsertanelementanywhereinanarraylist.B、Youcaninsertanelementanywhereinalinkedlist.C、Youcanusealinkedlisttoimproveefficiencyforaddingandremovingelementsatthebeginningofalist.D、Youshoulduseanarraylistifyourapplicationdoesnotrequireaddingandremovingelementsatthebeginningofalist.答案：ABCD解析：

暂无解析22.多选题SupposeAisanabstractclass,Bisaconcretesubclassof

A,andbothAandBhaveano-argconstructor.Whichofthefollowingiscorrect?()(1分)A、Aa=newA();B、Aa=newB();C、Bb=newA();D、Bb=newB();答案：BD解析：

暂无解析23.多选题Assumesis"ABCABC",themethod__________returnsanewstring"aBCaBC".()(1分)A、s.toLowerCase(s)B、s.toLowerCase()C、s.replace('A','a')D、s.replace('a','A')E、s.replace("ABCABC","aBCaBC")答案：CE解析：

暂无解析24.多选题Whichofthefollowingstatementsaretrue?()(1分)A、AnArrayListcangrowautomatically.B、AnArrayListcanshrinkautomatically.C、YoucanreducethecapacityofanArrayListbyinvokingthetrimToSize()methodonthelist.D、YoucanreducethecapacityofaLinkedListbyinvokingthetrimToSize()methodonthelist.答案：AC解析：

暂无解析25.多选题SupposeArrayListxcontainsthreestrings[Beijing,Singapore,Tokyo].Whichofthefollowingmethodswillcauseruntimeerrors?()(1分)A、x.get(2)B、x.set(3,"NewYork");C、x.get(3)D、x.remove(3)E、x.size()答案：BCD解析：

暂无解析26.多选题Whichofthefollowingarevalidspecifiersfortheprintfstatement?()(1分)A、%4cB、%10bC、%6dD、%8.2dE、%10.2e答案：ABCE解析：

暂无解析27.多选题Whichofthefollowingstatementsaretrue?()(1分)A、Multipleconstructorscanbedefinedinaclass.B、Constructorsdonothaveareturntype,notevenvoid.C、Constructorsmusthavethesamenameastheclassitself.D、Constructorsareinvokedusingthenewoperatorwhenanobjectiscreated.答案：ABCD解析：

暂无解析28.多选题Whichofthefollowingstatementsaretrue?(1分)A、TheComparableinterfacecontainsthecompareTomethodwiththesignature"publicintcompareTo(E)".B、TheComparatorinterfacecontainsthecomparemethodwiththesignature"publicintcompare(

E,E)".C、AComparableobjectcancomparethisobjectwiththeotherobject.D、AComparatorobjectcontainsthecomparemethodthatcomparestwoobjects.答案：ABCD解析：

暂无解析29.多选题Whyistheanalysisoftenfortheworstcase?()(1分)A、Best-caseisnotrepresentative.B、Worst-caseisnotrepresentative,butworst-caseanalysisisveryuseful.Youcanshowthatthealgorithmwillneverbeslowerthantheworst-case.C、Average-caseanalysisisideal,butdifficulttoperform,becauseitishardtodeterminetherelativeprobabilitiesanddistributionsofvariousinputinstancesformanyproblems.答案：ABC解析：

暂无解析30.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31.多选题Whichofthefollowingstatementsaretrue?()(1分)A、Asubclassisasubsetofasuperclass.B、Asubclassisusuallyextendedtocontainmorefunctionsandmoredetailedinformationthanitssuperclass.C、"classAextendsB"meansAisasubclassofBD、"classAextendsB"meansBisasubclassofA答案：BC解析：

暂无解析32.多选题Whichofthefollowingstatementsarecorrect?()(1分)A、Whenyoucreateanarrayusingnewint[10],anarrayobjectiscreatedwithtenintegersofvalue0.B、Whenyoucreateanarrayusingnewint[10],anarrayobjectiscreatedwithnovaluesinthearray.C、WhenyoucreateanArrayListusingnewArrayList(),anArrayListobjectiscreatedwithnoelementsintheArrayListobject.D、Whenyoucreateanarrayusingint[]x=newint[10],x.length()is10.E、WhenyoucreateanarrayusingArrayListx=newArrayList(10),x.size()is10.答案：ACD解析：

暂无解析33.多选题TheGeometricObjectandCircleclassesaredefinedinthischapter.Analyzethefollowingcode.Whichstatementsarecorrect?()

PublicclassTest{

Publicstaticvoidmain(String[]args){

GeometricObjectx=newCircle(3);

GeometricObjecty=(Circle)(x.clone());

System.out.println(x);

System.out.println(y);

}

}(1分)A、Theprogramhasacompileerrorbecausetheclone()methodisprotectedintheObjectclass.B、Afteryouoverridetheclone()methodandmakei