java认证之SCJP考试试题及答案讲解

Question1

Given:

11.publicinterfaceStatus{

12./*insertcodehere*/intMY_VALUE=10;

13.}

Whichthreearevalidonline12?(Choosethree.)

A.final

B.static

C.native

D.public

E.private

F.abstract

Gprotected

ABD

Question2

Given:

10.publicclassBar{

11.staticvoidfoo(int...x){

12.//insertcodehere

13.1

14.)

Whichtwocodefragments,insertedindependentlyatline12,willallow

theclasstocompile?(Choosetwo.)

A.foreach(x)System.out.println(z);

B.fdr(intz:x)System.out.println(z);

C.while(x.hasNext())System.out.println(x.next());

D.for(inti=0;i<x.length;i++)System.out.println(x[i]);

BD

Question3

Given:

11.publicclassTest{

12.publicstaticvoidmain(String[]args){

13.intx=5;

14.booleanbl=true;

15.booleanb2=false;

16.

17.if((x==4)&&!b2)

18.System.out.print(nl");

19.System.out.print(n2");

20.if((b2=true)&&bl)

21.System.out.print("3°);

22.)

23.}

Whatistheresult?

A.2

B.3

C.12

D.23

E.123

F.Compilationfails.

GAuexceptionalisthrownatruntime.

D

Question4

Given:

11.String[]elements={"for"，"tea"，"too"};

12.Stringfirst=(elements.length>0)?elements[0]:null;

Whatistheresult?

A.Compilationfails.

B.Anexceptionisthrownatruntime.

C.Thevariablefirstissettonull.

D.Thevariablefirstissettoelements[0].

D

Question5

Given:

10.interfaceFoo{}

11.classAlphaimplementsFoo{}

12.classBetaextendsAlpha{}

13.classDeltaextendsBeta{

14.publicstaticvoidmain(Stringf]args){

15.Betax=newBeta();

16.//insertcodehere

17.}

18.}

Whichcode,insertedatline16,willcausea

java.lang.ClassCastException?

A.Alphaa=x;隐式向上造型

B.Foof=(Delta)x;beta不能转换为delta

C.Foof=(Alpha)x;

D.Betab=(Beta)(Alpha)x;

B

Question6

Given:

11.classCup{}

12.classPoisonCupextendsCup{}

21.publicvoidtakeCup(Cupc){

22.if(cinstanceofPoisonCup){

23.System.out.println("Inconceivable!");

24.}elseif(cinstanceofCup){

25.System.out.println("Dizzyingintellect!1');

26.}else{

27.System.exit(O);

28.}

29.}

Andtheexecutionofthestatements:

Cupcup=newPoisonCupO;

takeCup(cup);

Whatistheoutput?

A.Inconceivable!

B.Dizzyingintellect!

C.Thecoderunswithnooutput.

D.Anexceptionisthrownatruntime.

E.Compilationfailsbecauseofanerrorinline22.

A

Question7

Given:

11.publicstaticvoidtest(Stringstr){

12.if(str=nullIstr.length()==0){〃空指针异常琲短路str.length()==O也会执行所

以空指针异常

13.System.out.println(nStringisempty");

14.}else{

15.System.out.println(''Stringisnotempty");

16.}

17.}

Andtheinvocation:

31.test(null);

Whatistheresult?

A.Anexceptionisthrownatruntime.

B."Stringisempty"isprintedtooutput.

C.Compilationfailsbecauseofauerrorinline12.

D."Stringisnotempty"isprintedtooutput.

A

Question8

Given:

10.publicclassMyClass{

11.

12.publicIntegerstartingl;

13.publicvoidmethodA(){

14.Integeri=newInteger(25);

15.startingl=i;

16.methodB(i);

17.)

18.privatevoidmethodB(Integeri2){

19.i2=Value();

20.

21.)

22.}

IfmethodAisinvoked,whichtwoaretrueatline20?(Choosetwo.)

A.i2==startinglreturnstrue.

B.i2==startinglreturnsfalse.

C.i2.equals(startingl)returnstrue.

D.i2.equals(startingl)returnsfalse.

BC

Question9

WhichManclassproperlyrepresentstherelationship"Manhasabest

friendwhoisaDog"?

A.classManextendsDog{}

B.classManimplementsDog{}

C.classMan{privateBestFrienddog;}

D.classMan{privateDogbestFriend;}

E.classMan{privateDog<bestFriend>}

F.classMan{privateBestFriend<dog>}〃无变量

D

Question10

Given:

11.publicclassItemTest{

12.privatefinalintid;

13.publicItemTest(intid){this.id=id;}

14.publicvoidupdateld(intnewld){id=newld;)

15.

16.publicstaticvoidmain(String[]args){

17.ItemTestfa=newItemTest(42);

18.fa.updateld(69);

19.System.out.println(fa.id);

20.)

21.)

Whatistheresult?

A.Compilationfails.

B.Anexceptionisthrownatruntime.

C.TheattributeidintheItemobjectremainsunchanged.

D.TheattributeidintheItemobjectismodifiedtothenewvalue.

E.AnewItemobjectiscreatedwiththepreferredvalueintheid

attribute.

A

Question11

Given:

15.publicclassYippee{

16.publicstaticvoidmain(String[]args){

17.for(intx=1;x<args.length;x++){

18.System.out.print(args[x]+””)；

19.}

20.}

21.)

andtwoseparatecommandlineinvocations:

javaYippee

javaYippee1234

Whatistheresult?

A.Nooutputisproduced.

123

B.Nooutputisproduced.

234

C.Nooutputisproduced.

1234

D.Anexceptionisthrownatruntime.

123

E.Anexceptionisthrownatruntime.

234

F.Anexceptionisthrownatrijntime.

1234

B

Question12

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=n+x++);

23.}

24.}

Whatistheresult?

A.Compilationfails.

B.Anexceptionisthrownatruntime.

C.doStuffx=6mainx=6

D.doStuffx=5mainx=5

E.doStuffx=5mainx=6

F.doStuffx=6mainx=5

D

Question13

Given:

10.packagecom.sun.scjp;

11.publicclassGeodetics{

12.publicstaticfinaldoubleDIAMETER=12756.32;//kilometers

13.}

WhichtwocorrectlyaccesstheDIAMETERmemberoftheGeodetics

class?(Choosetwo.)

A.importcom.sun.scjp.Geodetics;

publicclassTerraCarta{

publicdoublehalfwayO{returnGeodetics.DIAMETER/2.0;}}

B.importstaticcom.sun.scjp.Geodetics;

publicclassTerraCarta{

publicdoublehalfwayO{returnDIAMETER/2.0;}}

C.importstaticcom.sun.scjp.Geodetics.//static导入类中的所有静态成员

publicclassTerraCarta{

publicdoublehalfwayO{returnDIAMETER/2.0;}}

D.packagecom.sun.scjp;

publicclassTerraCarta{

publicdoublehalfwayO{returnDIAMETER/2.0;}}

AC

Question14

Given:

10.classNav{

11.publicenumDirection{NORTH,SOUTH,EAST,WEST}

12.)

13.publicclassSprite{

14.//insertcodehere

15.}

Whichcode,insertedatline14,allowstheSpriteclasstocompile?

A.Directiond=NORTH;

B.Nav.Directiond=NORTH;

C.Directiond=Direction.NORTH;

D.Nav.Directiond=Nav.Direction.NORTH;

D

Question15

Given:

10.interfaceFoo{intbar();}

11.publicclassSprite{

12.publicintfubar(Foofbo){returnfoo.bar();}

13.publicvoidtestFoo(){

14.fubar(

15.//insertcodehere

16.);

17.)

18.}

Whichcode,insertedatline15,allowstheclassSpritetocompile?

A.Foo{publicintbar(){return1;}}

B.newFoo{publicintbar(){return1;}}

C.newFoo(){publicintbar(){returnI;)}〃匿名类的使用

D.newclassFoo{publicintbar(){return1;})

C

Question16

Given:

11.publicclassCounter{

12.publicstaticvoidmain(String[]args){

13.intnumArgs=/*insertcodehere*/;

14.)

15.}

andthecommandline:

javaCounteronefred42

Whichcode,insertedatline13,capturesthenumberofarguments

passedintotheprogram?

A.args.count

B.args.length

C.args.count()

D.args.length()

E.args.getLength()

B

Question17

Given:

1.packagesun.sqp;

2.publicenumColor{RED,GREEN,BLUE}

1.packagesun.beta;

2.//insertcodehere

3.publicclassBeta)

4.Colorg=GREEN;

5.publicstaticvoidmain(String[]argv)

6.{System.out.println(GREEN);}

7.)

TheclassBetaandtheenumColorareindifferentpackages.

Whichtwocodefragments,insertedindividuallyatline2oftheBeta

declaration,willallowthiscodetocompile?(Choosetwo.)

A.importsun.scjp.Color.*;

B.importstaticsun.scjp.Color.*;

C.importsun.scjp.Color;importstaticsun.scjp.Color.*;

D.importsun.scjp.*;importstaticsun.scjp.Color.*;

E.importsun.scjp.Color;importstaticsun.scjp.Color.GREEN;

CDE

Question18

Given:

1.publicinterfaceA{

2.StringDEFAULT_GREETING="HelloWorld1';

3.publicvoidmethod1();

4.}

AprogrammerwantstocreateaninterfacecalledBthathasAasits

parent.Whichinterfacedeclarationiscorrect?

A.publicinterfaceBextendsA{}

B.publicinterfaceBimplementsA{}

C.publicinterfaceBinstanceOfA{}

D.publicinterfaceBinheritsFromA{}

A

Question19

Given:

1.classTestA{

2.publicvoidstart(){System.out.println(nTestAH);}

3.}

4.publicclassTestBextendsTestA{

5.publicvoidstart(){System.out.println("TestBH);}

6.publicstaticvoidmain(String[]args){

7.((TestA)newTestB()).start();//TestB对象

8.}

9.}

Whatistheresult?

A.TestA

B.TestB

C.Compilationfails.

D.Anexceptionisthrownatruntime.

B

Question20

Given:

1.interfaceTestA{StringtoStringO;}

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.Compilationfailsbecauseofanenorinline5.

A

Question21

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(10J0);

s.draw();

B.Circlec=newShape();

c.setAnchor(10,10);

c.draw();

C.Shapes=newCircle();

s.setAnchor(IOJO);

s.draw();

D.Shapes=newCircle();

s->setAnchor(10,10);

s->draw();

E.Circlec=newCircle();

c.Shape.setAnchor(10,10);

c.Shape.draw();

C

Question22

Given:

10.abstractpublicclassEmployee{

11.protectedabstractdoublegetSalesAmount();

12.publicdoublegetCommision(){

13.returngetSalesAmount()*0.15;

14.}

15.}

16.classSalesextendsEmployee{

17.//insertmethodhere

18.}

Whichtwomethods,insertedindependentlyatline17,correctly

completetheSalesclass?(Choosetwo.)

A.doublegetSalesAmount(){return1230.45;}

B.publicdoublegetSalesAmount(){return1230.45;}

C.privatedoublegetSalesAmount(){return1230.45;}

D.protecteddoublegetSalesAmount(){return1230.45;}

BD

Question23

Given:

10.interfaceData{publicvoidload();}

11.abstractclassInfo{publicabstractvoidload();}

WhichclasscorrectlyusestheDatainterfaceandInfoclass?

A.publicclassEmployeeextendsInfbimplementsData{

publicvoidload(){/*dosomething*/}

)

B.publicclassEmployeeimplementsInfoextendsData)

publicvoidload(){/*dosomething*/}

)

C.publicclassEmployeeextendsInfoimplementsData{

publicvoidload(){/*dosomething*/}

publicvoidlnfo.load(){/*dosomething*/}

)

D.publicclassEmployeeimplementsInfoextendsData{

publicvoidData.load(){/*dsomething*/}

publicvoidload(){/*dosomething*/}

)

E.publicclassEmployeeimplementsInfoextendsData{

publicvoidload(){/*dosomething*/}

publicvoidInfo.load(){/*dosomething*/}

)

F.publicclassEmployeeextendsInfbimplementsData{

publicvoidData.load(){/*dosomething*/}

publicvoidInfo.load(){/*dosomething*/}

)

A

Question24

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*/}

)

BE

Question25

Whichtwoclassescorrectlyimplementboththejava.lang.Runnable

andthejava.lang.Clonableinterfaces?(Choosetwo.)

A.publicclassSession

implementsRunnable,Clonable{

publicvoidrun();

publicObjectclone();

)

B.publicclassSession

extendsRunnable,Clonable{

publicvoidrun(){/dosomething*/}

publicObjectclone(){/makeacopy*/}

)

C.publicclassSession

implementsRunnable,Clonable{

publicvoidrun(){/dosomething*/}

publicObjectclone(){/*makeacopy*/}

)

D.publicabstractclassSession

implementsRunnable,Clonable{

publicvoidrun(){/dosomething*/)

publicObjectclone(){/*makeacopy*/}

)

E.publicclassSession

implementsRunnable,implementsClonable{

publicvoidrun(){/dosomething*/)

publicObjectclone(){/makeacopy*/}

)

CD

Question26

1.publicclassGoTest{

2.publicstaticvoidmain(String[]args){

3.Sentea=newSente();a.go();

4.Gobanb=newGoban();b.go();

5.Stonec=newStone();c.go();

6}

7.}

8.

9.classSenteimplementsGo{

10.publicvoidgo(){System.out.println(ngoinSente.'1);}

H.)

12.

13.classGobanextendsSente{

14.publicvoidgo(){System.out.print]n(HgoinGoban");}

15.}

16.

17.classStoneextendsGobanimplementsGo{}

18.

19.interfaceGo{publicvoidgo();}

Whatistheresult?

A.goinGoban

goinSente

goinSente

B.goinSente

goinSente

goinGoban

C.goinSente

goinGoban

goinGoban

D.goinGoban

goinGoban

goinSente

E.Compilationfailsbecauseofanerrorinline17.

C

Question27

Given:

11.publicstaticvoidparse(Stringstr){

12.try{

13.floatf=Float.parseFloat(str);

14.}catch(NumberFormatExceptionnfe){

15.f=0;〃f在try里定义这里找不到f

16.}finally{

17.System.out.println(f)；

18.}

19.)

20.publicstaticvoidmain(String[]args){

21.parse(uinvalid");

22.}

Whatistheresult?

A.0.0

B.Compilationfails.

C.AParseExceptionisthrownbytheparsemethodatruntime.

D.ANumberFormatExceptionisthrownbytheparsemethodat

runtime.

B

Question28

1.publicclassTest{

2.intx=12;

3.publicvoidmethod(intx){

4.x+=x;

5.System.out.println(x);

6.)

7J

Given:

34.Testt=newTest();

35.t.method(5);

Whatistheoutputfromline5oftheTestclass?

A.5

B.10

C.12

D.17

E.24

B

Question29

Given:

55.int[]x={1,2,34,5};

56.inty[]=x;

57.System.out.println(y[2J);

Whichistrue?

A.Line57willprintthevalue2.

B.Line57willprintthevalue3.

C.Compilationwillfailbecauseofanerrorinline55.

D.Compilationwillfailbecauseofanerrorinline56.

B

Question30

Given:

35.String#name="JaneDoe";

36.int$age=24;

37.Double_height=123.5;

38.double〜temp=37.5;

Whichtwoaretrue?(Choosetwo.)

A.Line35willnotcompile.

B.Line36willnotcompile.

C.Line37willnotcompile.

D.Line38willnotcompile.

AD

Question31

Whichtwocodefragmentscorrectlycreateandinitializeastaticarray

ofintelements?(Choosetwo.)

A.staticfinalint[]a={100,200};

B.staticfinalint[]a;

static{a=newint[2];a[0]=100;a[l]=200;}

C.staticfinalint[]a=newint[2]{100,200};〃后面已初始int[2]不能给大小

D.staticfinalint[]a;

staticvoidinit(){a=newint[3];a[0]=100;a[l]=200;}

AB

Question32

Given:

11.publicclassBall{

12.publicenumColor{RED,GREEN,BLUE};

13.publicvoidfoo(){

14.//insertcodehere

15.{System.out.println(c);}

16.}

17.}

Whichcodeinsertedatline14causesthefoomethodtoprintRED,

GREEN,andBLUE?

A.for(Colorc:Color,values。)〃枚举的方法

B.for(Colorc=RED;c<=BLUE;C++)

C.for(Colorc;c.hasNext();c.next())

D.for(Colorc=Color[0];c<=Color[2];C++)

E.for(Colorc=Color.RED;c<=Color.BLUE;C++)

A

Question33

Given:

10.publicclassFabric

11.publicenumColor{

12.RED(OxfroOOO),GREEN(OxOOfroO),BLUE(0x0000ff);

13.privatefinalintrgb;

14.Color(intrgb){this.rgb=rgb;}

15.publicintgetRGB(){returnrgb;}

16.);

17.publicstaticvoidmain(String[]argv){

18.//insertcodehere

19.}

20.}

Whichtwocodefragments,insertedindependentlyatline18,allowthe

Fabricclasstocompile?(Choosetwo.)

A.ColorskyColor=BLUE;

B.ColortreeColor=Color.GREEN;

C.Colorpurple=newColor(OxffOOff);

D.if(RED.getRGB()<BLUE.getRGB()){}

E.Colorpurple=Color.BLUE+Color.RED;

F.if(Color.RED.ordinal()<Color.BLUE.ordinal()){}〃ordinal()下标方法

BF

单例模式的两种方法：

classA

(

privatestaticAa=newA();

privateA()

{

)

publicstaticAgetInstance()

(

returna;

)

)

classA

{

privatestaticAa;

privateA()

}

publicstaticAgetInstance()

{

if(a==nul1)

(

a=newA();

)

returna;

)

)

Question34

Givenclassesdefinedintwodifferentfiles:

1.packageutil;

2.publicclassBitUtils{

3.publicstaticvoidprocess(byte[]){/*morecodehere*/}

4.)

1.packageapp;

2.publicclassSomeApp{

3.publicstaticvoidmain(String[]args){

4.byte[]bytes=newbyte[256J;

5.//insertcodehere

6.)

7.}

Whatisrequiredatline5inclassSomeApptousetheprocessmethod

ofBitUtils?

A.process(bytes);

B.BitUcess(bytes);

C.util.BitUcess(bytes);

D.SomeAppcannotusemethodsinBitUtils.

E.importutil.BitUtils.*;process(bytes);

C

Question35

Given:

11.publicstaticvoidmain(String[]args){

12.Objectobj=newint[]{1,2,3);

13.int[]someArray=(int[])obj;

14.for(inti:someArray)System.out.print(i+“”)；

15.}

Whatistheresult?

A.123

B.Compilationfailsbecauseofanerrorinline12.

C.Compilationfailsbecauseofanerrorinline13.

D.Compilationfailsbecauseofanerrorinline14.

E.AClassCastExceptionisthrownatruntime.

A

Question36

Given:

10.classFoo{

11.staticvoidalpha(){/*morecodehere*/}

12.voidbeta(){/*morecodehere*/}

13.}

Whichtwoaretrue?(Choosetwo.)

A.Foo.beta()isavalidinvocationofbeta().

B.Foo.alpha()isavalidinvocationofalpha().

C.Methodbeta()candirectlycallmethodalpha().

D.Methodalpha()candirectlycallmethodbeta().

CB

Question37

Aprogrammerneedstocreatealoggingmethodthatcanacceptan

arbitrarynumberofarguments.Forexample,itmaybecalledinthese

ways:

loglt(nlogmessage1");

loglt(nlogmessage2","logmessages'1);

logIt(Mlogmessaged","logmessage5n,"logmessage6);

Whichdeclarationsatisfiesthisrequirement?

A.publicvoidlogIt(String*msgs)

B.publicvoidloglt(String[]msgs)

C.publicvoidloglt(String...msgs)

D.publicvoidlogIt(Stringmsgl,Stringmsg2,Stringmsg3)

C

Question38

Aprogrammerisdesigningaclasstoencapsulatetheinformation

aboutaninventoryitem.AJavaBeanscomponentisneededto

dothis.TheInventoryitemclasshasprivateinstancevariablestostore

theiteminformation:

10.privateintitemld;

11.privateStringname;

12.privateStringdescription;

WhichmethodsignaturefollowstheJavaBeansnamingstandardsfor

modifyingtheitemldinstancevariable?

A.itemID(intitemld)

B.update(intitemld)

C.setltemld(intitemld)

D.mutateltemld(intitemld)

E.updateItemID(intitemld)

C

Question39

1.publicclassA{

2.

3.privateintcounter=0;

4.

5.publicstaticintgetInstanceCount(){

6.returncounter;〃静态方法里不能使用非静态变量

7.}

8.

9.publicA(){

10.counter++;

H.)

12.

13.}

GiventhiscodefromClassB:

25.Aal=newA();

26.Aa2=newA();

27.Aa3=newA();

28.System.out.printIn(A.getInstanceCount());

Whatistheresult?

A.CompilationofclassAfails.

B.Line28printsthevalue3toSystem.out.

C.Line28printsthevalue1toSystem.out.

D.Aruntimeerroroccurswhenline25executes.

E.Compilationfailsbecauseofanerroronline28.

A

Question40

AJavaBeanscomponenthasthefollowingfield:

11.privatebooleanenabled;

WhichtwopairsofmethoddeclarationsfollowtheJavaBeansstandard

foraccessingthisfield?(Choosetwo.)

A.publicvoidsetEnabled(booleanenabled)

publicbooleangetEnabled()

B.publicvoidsetEnabled(booleanenabled)

publicvoidisEnabled()

C.publicvoidsetEnabled(booleanenabled)

publicbooleanisEnabled()

D.publicbooleansetEnabled(booleanenabled)

publicbooleangetEnabled()

AC

Question41

41.Given:

10.classOne{

11.publicOnefoo(){returnthis;)

12.)

13.classTwoextendsOne{

14.publicOnefoo(){returnthis;}

15.}

16.classThreeextendsTwo{

17.//insertmethodhere

18.}

Whichtwomethods,insertedindividually,correctlycompletetheThreeclass?(Choosetwo.)

A.publicvoidfoo(){}

B.publicintfoo(){return3;}

C.publicTwofoo(){returnthis;}

D.publicOnefoo(){returnthis;}

E.publicObjectfoo(){returnthis;}

CD

Question42

Given:

10.classOne{

11.voidfoo(){}

12.)

13.classTwoextendsOne{

14.//insertmethodhere

15.}

Whichthreemethods,insertedindividuallyatline14,willcorrectly

completeclassTwo?(Choosethree.)

A.intfoo(){/*morecodehere*/}

B.voidfoo(){/*morecodehere*/}

C.publicvoidfoo(){/*morecodehere*/}

D.privatevoidfoo(){/*morecodehere*/}

E.protectedvoidfoo(){/*morecodehere*/)

BCE

Question43

1.publicinterfaceA{

2.publicvoiddoSomething(Stringthing);

3.}

1.publicclassAlmplimplementsA{

2.publicvoiddoSomething(Stringmsg){}

3.}

1.publicclassB{

2.publicAdoit(){

3.//morecodehere

4.}

5.

6.publicStringexecute(){

7.//morecodehere

8.}

9.}

1.publicclassCextendsB{

2.publicAlmpldoit(){

3.//morecodehere

4.}

5.

6.publicObjectexecute(){〃不能重写

7.//morecodehere

8.}

9.}

Whichstatementistrueabouttheclassesandinterfacesinthe

exhibit?

A.Compilationwillsucceedforallclassesandinterfaces.

B.CompilationofclassCwillfailbecauseofanerrorinline2.

C.CompilationofclassCwillfailbecauseofanerrorinline6.

D.CompilationofclassAlmplwillfailbecauseofanerrorinline2.

C

Question44

1.publicclassA{

2.publicStringdoit(intx,inty){

3.return"a";

4.)

5.

6.publicStringdoit(int...vals){

7.return"b";

8.)

9.)

Given:

25.Aa=newA();

26.System.out.println(a.doit(4,5));

Whatistheresult?

A.Line26prints"a"toSystem.out.

B.Line26prints"b"toSystem.out.

C.Anexceptionisthrownatline26atruntime.

D.CompilationofclassAwillfailduetoanerrorinline6.

A

Question45

Given:

1.publicclassA{

2.publicvoiddoit(){

3.}

4.publicStringdoit(){〃不构成重载不能同时存在，参数列表相同

5.return"a";

6.)

7.publicdoubledoit(intx){

8.return1.0;

9.}

10.}

Whatistheresult?

A.Anexceptionisthrownatruntime.

B.Compilationfailsbecauseofanerrorinline7.

C.Compilationfailsbecauseofanerrorinline4.

D.CompilationsucceedsandnoruntimeerrorswithclassAoccur.

C

Question46

46.Given:

10.classLine{

11.publicstaticclassPoint{}

12.}

13.

14.classTriangle{

15.//insertcodehere

16.}

Whichcode,insertedatline15,createsaninstanceofthePointclass

definedinLine?

A.Pointp=newPoint();

B.Line.Pointp=newLine.Point();

C.ThePointclasscannotbeinstatiatedatline15.

D.Line1=newLine();1.Pointp=newl.Point();

B

Question47

Given:

10.classLine{

11.publicclassPoint{publicintx,y;}

12.publicPointgetPoint(){returnnewPoint();}

13.}

14.classTriangle{

15.publicTriangle(){

16.//insertcodehere

17.)

18.}

Whichcode,insertedatline16,correctlyretrievesalocalinstanceofa

Pointobject?

A.Pointp=Line.getPoint();

B.Line.Pointp=Line.getPoint();

C.Pointp=(newLine()).getPoint();

D.Line.Pointp=(newLine()).getPoint();

D

Question48

Given:

10.classOne{

11.publicOne(){System.out.print(l);}

12.)

13.classTwoextendsOne{

14.publicTwo(){System.out.print(2);}

15.)

16.classThreeextendsTwo{

17.publicThree(){System.out.print(3);}

18.}

19.publicclassNumbers{

20.publicstaticvoidmain(String[]argv){newThree();}

21.)

Whatistheresultwhenthiscodeisexecuted?

A.1

B.3

C.123

D.321

E.Thecoderimswithnooutput.

C

Question49

11.classPerson{

12.Stringname="Noname";

13.publicPerson(Stringnm){name=nm;}〃不是无参构造方法

14.}

15.

16.classEmployeeextendsPerson{

17.StringemplD="0000H;

18.publicEmployee(Stringid){emplD=id;}〃要用super

19.)

20.

21.publicclassEmployeeTest)

22.publicstaticvoidmain(String[]args){

23.Employeee=newEmployee(“4321")；

24.System.out.println(e.empID);

25.}

26.}

Whatistheresult?

A.4321

B.0000

C.Anexceptionisthrownatruntime.

D.Compilationfailsbecauseofanerrorinline18.

D

Question50

Given:

1.publicclassPlant{

2.privateStringname;

3.publicPlant(Stringname){=name;}

4.publicStringgetName(){retumname;}

5.)

1.publicclassTreeextendsPlant{

2.publicvoidgrowFruit(){}

3.publicvoiddropLeaves(){}

4.}

Whichistrue?

A.Thecodewillcompilewithoutchanges.

B.ThecodewillcompileifpublicTree(){Plant();}isaddedtothe

Treeclass.

C.ThecodewillcompileifpublicPlant(){Tree();}isaddedtothe

Plantclass.

D.ThecodewillcompileifpublicPlant(){this(Hfern");}isaddedto

thePlantclass.

E.ThecodewillcompileifpublicPlant(){Plant(',femn);}isaddedto

thePlantclass.

D

Question51

11.publicclassBootchy{

12.intbootch;

13.Stringsnootch;

14.

15.publicBootchyO{

16.thisC^nootchy");

17.System.out.print("firstu);

18.)

19.

20.publicBootchy(Stringsnootch){

21.this(420,"snootchy1');

22.System.out.print(nsecond");

23.}

24.

25.publicBootchy(intbootch,Stringsnootch){

26.this.bootch=bootch;

27.this.snootch=snootch;

28.System.out.print("third”)；

29.}

30.

31.publicstaticvoidmain(String[]args){

32.Bootchyb=newBootchyO;

33.System.out.print(b.snootch+"H+b.bootch);

34.}

35.}

Whatistheresult?

A.snootchy420thirdsecondfirst

B.snootchy420firstsecondthird

C.firstsecondthirdsnootchy420

D.thirdsecondfirstsnootchy420

E.thirdfirstsecondsnootchy420

F.firstsecondfirstthirdsnootchy420

D

Question52