java OOP习题测试.docx
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java OOP习题测试.docx
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javaOOP习题测试
Question1
Given:
11.publicinterfaceStatus{
12./*insertcodehere*/intMY_VALUE=10;
13.}
Whichthreearevalidonline12?
(Choosethree.)DAB
A.finalB.staticC.nativeD.publicE.privateF.abstractG.protected
Question2
Given:
11.publicclassTest{
12.publicstaticvoidmain(String[]args){
13.intx=5;
14.booleanb1=true;
15.booleanb2=false;
16.
17.if((x==4)&&!
b2)
18.System.out.print(“l“);
19.System.out.print(“2”);
20.if((b2=true)&&b1)
21.System.out.print(“3“);
22.}
23.}
Whatistheresult?
A.2B.3C.12D.23E.123F.Compilationfails.
G.Auexceptionalisthrownatruntime.
Question3
Given:
10.interfaceFoo{}
11.classAlphaimplementsFoo{}
12.classBetaextendsAlpha{}
13.classDeltaextendsBeta{
14.publicstaticvoidmain(String[]args){
15.Betax=newBeta();
16.//insertcodehere
17.}
18.}
Whichcode,insertedatline16,willcauseajava.lang.ClassCastException?
A.Alphaa=x;
B.Foof=(Delta)x;
C.Foof=(Alpha)x;
D.Betab=(Beta)(Alpha)x;
Question4
Given:
20.publicclassCreditCard{
21.privateStringcardlD;
22.privateIntegerlimit;
23.publicStringownerName;
24.
25.publicvoidsetCardlnformation(StringcardlD,StringownerName,Integerlimit){
26.this.cardlD=cardlD;
30.this.ownerName=ownerName;
31.this.limit=limit;
32.}
33.}
Whichistrue?
A.Theclassisfullyencapsulated.
B.Thecodedemonstratespolymorphism.
C.TheownerNamevariablebreaksencapsulation.
D.ThecardlDandlimitvariablesbreakpolymorphism.
E.ThesetCardlnformationmethodbreaksencapsulation.
Question5
Assumethatcountryissetforeachclass.
Given:
10.publicclassMoney{
11.privateStringcountry,name;
12.publicStringgetCountry(){returncountry;}
13.}
and:
24.classYenextendsMoney{
25.publicStringgetCountry(){returnsuper.country;}
26.}
27.
28.classEuroextendsMoney{
29.publicStringgetCountry(StringtimeZone){
30.returnsuper.getCountry();
31.}
32.}
Whichtwoarecorrect?
(Choosetwo.)
A.Yenreturnscorrectvalues.
B.Euroreturnscorrectvalues.
C.Anexceptionisthrownatruntime.
D.YenandEurobothreturncorrectvalues.
E.Compilationfailsbecauseofanerroratline25.
F.Compilationfailsbecauseofanerroratline30.
Question6
WhichManclassproperlyrepresentstherelationship“ManhasabestfriendwhoisaDog”?
A.classManextendsDog{}
B.classManimplementsDog{}
C.classMan{privateBestFrienddog;}
D.classMan{privateDogbestFriend;}
E.classMan{privateDog
F.classMan{privateBestFriend
Question7
Given:
23.Object[]myObjects={
24.newInteger(12),
25.newString(”foo”),
26.newInteger(5),
27.newBoolean(true)
28.};
29.Arrays.sort(myObjects);
30.for(inti=0;i 31.System.out.print(myObjects[i].toString()); 32.System.out.print(”“); 33.} Whatistheresult? A.Compilationfailsduetoanerrorinline23. B.Compilationfailsduetoanerrorinline29. C.AClassCastExceptionoccursinline29. D.AClassCastExceptionoccursinline31. E.Thevalueofallfourobjectsprintsinnaturalorder. Question8 12.Given: 13.publicclassPass{ 14.publicstaticvoidmain(String[]args){ 15.intx=5; 16.Passp=newPass(); 17.p.doStuff(x); 18.System.out.print(”mainx=“+x); 19.} 20. 21.voiddoStuff(intx){ 22.System.out.print(”doStuffx=“+x++); 23.} 24.} Whatistheresult? A.Compilationfails. B.Anexceptionisthrownatruntime. C.doStuffx=6mainx=6 D.doStuffx=5mainx=5 E.doStuffx=5mainx=6 F.doStuffx=6mainx=5 Question9 Given: 10.packagecom.sun.scjp; 11.publicclassGeodetics{ 12.publicstaticfinaldoubleDIAMETER=12756.32;//kilometers 13.} WhichtwocorrectlyaccesstheDIAMETERmemberoftheGeodeticsclass? (Choosetwo.) A.importcom.sun.scjp.Geodetics; publicclassTerraCarta{ publicdoublehalfway(){returnGeodetics.DIAMETER/2.0;} } B.importstaticcom.sun.scjp.Geodetics; publicclassTerraCarta{ publicdoublehalfway(){returnDIAMETER/2.0;} } C.importstaticcom.sun.scjp.Geodetics.*; publicclassTerraCarta{ publicdoublehalfway(){returnDIAMETER/2.0;} } D.packagecom.sun.scjp; publicclassTerraCarta{ publicdoublehalfway(){returnDIAMETER/2.0;} } Question10 ClicktheExhibitbutton. 10.interfaceFoo{ 11.intbar(); 12.} 13. 14.publicclassBeta{ 15. 16.classAimplementsFoo{ 17.publicintbar(){return1;} 18.} 19. 20.publicintfubar(Foofoo){returnfoo.bar();} 21. 22.publicvoidtestFoo(){ 23. 24.classAimplementsFoo{ 25.publicintbar(){return2;} 26.} 27. 28.System.out.println(fubar(newA())); 29.} 30. 31.publicstaticvoidmain(String[]argv){ 32.newBeta().testFoo(); 33.} 34.} Whichthreestatementsaretrue? (Choosethree.) A.Compilationfails. B.Thecodecompilesandtheoutputis2. C.Iflines16,17and18wereremoved,compilationwouldfail. D.Iflines24,25and26wereremoved,compilationwouldfail. E.Iflines16,17and18wereremoved,thecodewouldcompileandtheoutputwouldbe2. F.Iflines24,25and26wereremoved,thecodewouldcompileandtheoutputwouldbe1. Question11 Given: 1.publicinterfaceA{ 2.StringDEFAULT_GREETING=“HelloWorld”; 3.publicvoidmethod1(); 4.} AprogrammerwantstocreateaninterfacecalledBthathasAasitsparent.Whichinterfacedeclarationiscorrect? A.publicinterfaceBextendsA{} B.publicinterfaceBimplementsA{} C.publicinterfaceBinstanceOfA{} D.publicinterfaceBinheritsFromA{} Question12 Given: 1.classTestA{ 2.publicvoidstart(){System.out.println(”TestA”);} 3.} 4.publicclassTestBextendsTestA{ 5.publicvoidstart(){System.out.println(”TestB”);} 6.publicstaticvoidmain(String[]args){ 7.((TestA)newTestB()).start(); 8.} 9.} Whatistheresult? A.TestA B.TestB C.Compilationfails. D.Anexceptionisthrownatruntime. Question13 Given: 1.interfaceTestA{StringtoString();} 2.publicclassTest{ 3.publicstaticvoidmain(String[]args){ 4.System.out.println(newTestA(){ 5.publicStringtoString(){return“test”;} 6.}); 7.} 8.} Whatistheresult? A.test B.null C.Anexceptionisthrownatruntime. D.Compilationfailsbecauseofanerrorinline1. E.Compilationfailsbecauseofanerrorinline4. F.Compilationfailsbecauseofanerrorinline5. Question14 Given: 11.publicabstractclassShape{ 12.intx; 13.inty; 14.publicabstractvoiddraw(); 15.publicvoidsetAnchor(intx,inty){ 16.this.x=x; 17.this.y=y; 18.} 19.} andaclassCirclethatextendsandfullyimplementstheShapeclass.Whichiscorrect? A.Shapes=newShape(); s.setAnchor(10,10); s.draw(); B.Circlec=newShape(); c.setAnchor(10,10); c.draw(); C.Shapes=newCircle(); s.setAnchor(10,10); s.draw(); D.Shapes=newCircle(); s->setAnchor(10,10); s->draw(); E.Circlec=newCircle(); c.Shape.setAnchor(10,10); c.Shape.draw(); Question15 Given: 10.abstractpublicclassEmployee{ 11.protectedabstractdoublegetSalesAmount(); 12.publicdoublegetCommision(){ 13.returngetSalesAmount()*0.15; 14.} 15.} 16.classSalesextendsEmployee{ 17.//insertmethodhere 18.} Whichtwomethods,insertedindependentlyatline17,correctlycompletetheSalesclass? (Choosetwo.) A.doublegetSalesAmount(){return1230.45;} B.publicdoublegetSalesAmount(){return1230.45;} C.privatedoublegetSalesAmount(){return1230.45;} D.protecteddoublegetSalesAmount(){return1230.45;} Question16 Given: 10.interfaceData{publicvoidload();} 11.abstractclassInfo{publicabstractvoidload();} WhichclasscorrectlyusestheDatainterfaceandInfoclass? A.publicclassEmployeeextendsInfoimplementsData{ publicvoidload(){/*dosomething*/} } B.publicclassEmployeeimplementsInfoextendsData{ publicvoidload(){/*dosomething*/} } C.publicclassEmployeeextendsInfoimplementsData{ publicvoidload(){/*dosomething*/} publicvoidInfo.load(){/*dosomething*/} } D.publicclassEmployeeimplementsInfoextendsData{ publicvoidData.load(){/*dsomething*/} publicvoidload(){/*dosomething*/} } E.publicclassEmployeeimplementsInfoextendsData{ publicvoidload(){/*dosomething*/} publicvoidInfo.load(){/*dosomething*/} } F.publicclassEmployeeextendsInfoimplementsData{ publicvoidData.load(){/*dosomething*/} publicvoidInfo.load(){/*dosomething*/} } Question17 Given: 11.publicabstractclassShape{ 12.privateintx; 13.privateinty; 14.publicabstractvoiddraw(); 15.publicvoidsetAnchor(intx,inty){ 16.this.x=x; 17.this.y=y; 18.} 19.} WhichtwoclassesusetheShapeclasscorrectly? (Choosetwo.) A.publicclassCircleimplementsShape{ privateintradius; } B.publicabstractclassCircleextendsShape{ privateintradius; } C.publicclassCircleextendsShape{ privateintradius; publicvoiddraw(); } D.publicabstractclassCircleimplementsShape{ privateintradius; publicvoiddraw(); } E.publicclassCircleextendsShape{ privateintradius; publicvoiddraw(){/*codehere*/} } F.publicabstractclassCircleimplementsShape{ privateintradius; publicvoiddraw(){/codehere*/} } Question18 Whichtwoclassescorrectlyimplementboththejava.lang.Runnableandthejava.lang.Clonableinterfa
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