SCJP题库.docx

SCJP题库.docx

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SCJP题库

yModule1-JAVA基础

一、选择题：

Question1

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.

Answer:

AD标识符以字母，下划线，或者$开始

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.2

B.3

C.12

D.23

E.123

F.Compilationfails.

G.Anexceptionalisthrownatruntime.

Answer:

D注意20行，=为赋值，不要被骗

Question3

Given:

42.publicclassClassA{

43.publicintgetValue（）{

44.intvalue=0;

45.booleansetting=true;

46.Stringtitle="Hello";

47.if（value||（setting&&title=="Hello"））{return1;}

48.if（value==1&title.equals（"Hello"））{return2;}

49.}

50.}

And:

70.ClassAa=newClassA（）;

71.a.getValue（）;

Whatistheresult?

A.1

B.2

C.Compilationfails.

D.Thecoderunswithnooutput.

E.Anexceptionisthrownatruntime.

Answer:

C编译不通过，47行value为int类型不是boolean

Question4

Given:

11.publicvoidtestIfA（）{

12.if（testIfB（"True"））{

13.System.out.println（"True"）;

14.}else{

15.System.out.println（"Nottrue"）;

16.}

17.}

18.publicBooleantestIfB（Stringstr）{

19.returnBoolean.valueOf（str）;

20.}

WhatistheresultwhenmethodtestIfAisinvoked?

A.True

B.Nottrue

C.Anexceptionisthrownatruntime.

D.Compilationfailsbecauseofanerroratline12.

E.Compilationfailsbecauseofanerroratline19.

Answer:

A19行，如果str为true则返回ture，否则返回false

Question5

Given:

11.publicstaticvoidmain（String[]args）{

12.Integeri=newInteger

（1）+newInteger

（2）;

13.switch（i）{

14.case3:

System.out.println（"three"）;break;

15.default:

System.out.println（"other"）;break;

16.}

17.}

Whatistheresult?

A.three

B.other

C.Anexceptionisthrownatruntime.

D.Compilationfailsbecauseofanerroronline12.

E.Compilationfailsbecauseofanerroronline13.

F.Compilationfailsbecauseofanerroronline15.

Answer:

A就是两个Integer类型相加

Question6

Given:

11.publicstaticvoidmain（String[]args）{

12.Stringstr="null";

13.if（str==null）{

14.System.out.println（"null"）;

15.}else（str.length（）==0）{

16.System.out.println（"zero"）;

17.}else{

18.System.out.println（"some"）;

19.}

20.}

‘Whatistheresult?

A.null

B.zero

C.some

D.Compilationfails.

E.Anexceptionisthrownatruntime.

Answer:

D这题真恶心15行少个if

Question7

Given:

10.intx=0;

11.inty=10;

12.do{

l3.y--;

14.++x;

15.}while（x<5）;

16.System.out.print（x+","+y）;

Whatistheresult?

A.5,6

B.5,5

C.6,5

D.6,6

Answer:

B（91，82，73，64，55）没啥争议

Question8

Given:

25.intx=12;

26.while（x<10）{

27.x--;

28.}

29.System.out.print（x）;

Whatistheresult?

A.0

B.10

C.12

D.Line29willneverbereached.

Answer:

C12>10，所以直接跳出循环，输出x=12

Question9

Given:

35.intx=10;

36.do{

37.x--;

38.}while（x<10）;

Howmanytimeswillline37beexecuted?

A.tentimes

B.zerotimes

C.onetometimes

D.morethantentimes

Answer:

D死循环

Question10

Given:

11.publicstaticvoidmain（String[]args）{

12.for（inti=0;i<=10;i++）{

13.if（i>6）break;

14.}

15.System.out.println（i）;

16.}

Whatistheresult?

A.6

B.7

C.10

D.11

E.Compilationfails.

F.Anexceptionisthrownatruntime.

Answer:

E15行i超出了作用域

Question11

Given:

55.int[]x={1,2,3,4,5};

56.inty[]=x;

57.System.out.println（y[2]）;

Whichistrue?

A.Line57willprintthevalue2.

B.Line57willprintthevalue3.

C.Compilationwillfailbecauseofanerrorinline55.

D.Compilationwillfailbecauseofanerrorinline56.

Answer:

B没争议，考察数组下标是从0开始

Question12

Whichtwocodefragments（片段）correctly（正确）createandinitializeastaticarrayofintelements?

（Choosetwo.）

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

B.staticfinalint[]a;

static{a=newint[2];a[0]=100;a[1]=200;}

C.staticfinalint[]a=newint[2]{100,200};

D.staticfinalint[]a;

staticvoidinit（）{a=newint[3];a[0]=100;a[1]=200;}

Answer:

ABc不能指定长度，d不能在init方法中赋值，要么在static代码块中

Question13

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.

Answer:

A没争议，foeach循环遍历数组

Question14

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].

Answer:

D

Question15

Given:

10.publicclassBar{

11.staticvoidfoo（int...x）{

12.//insertcodehere

13.}

14.}

Whichtwocodefragments,insertedindependently（独立的）atline12,willallowtheclasstocompile?

（Choosetwo.）

A.foreach（x）System.out.println（z）;

B.for（intz:

x）System.out.println（z）;

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

D.for（inti=0;i

Answer:

BDx相当于一个数组，a明显错没有foreach，c中x没有hadNext方法

Question16

Aprogrammer（程序员）needstocreatealoggingmethodthatcanaccept（接受）anarbitrary（随意任意）numberofarguments.Forexample,itmaybecalledinthese

ways:

logIt（"logmessage1"）;

logIt（"logmessage2”,”logmessage3"）;

logIt（"logmessage4","logmessage5","logmessage6"）;

Whichdeclaration（说明）satisfies（符合）thisrequirement（需求）?

A.publicvoidlogIt（String*msgs）

B.publicvoidlogIt（String[]msgs）

C.publicvoidlogIt（String...msgs）

D.publicvoidlogIt（Stringmsg1,Stringmsg2,Stringmsg3）

Answer:

C可变长参数

Question17

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.

Answer:

A确定参数和可变长参数同时存在的时候，优先考虑确定参数的

Question18

GivenafileGrizzlyBear.java:

1.packageanimals.mammals;

2.

3.publicclassGrizzlyBearextendsBear{

4.voidhunt（）{

5.Salmons=findSalmon（）;

6.s.consume（）;

7.}

8.}

andanotherfile,Salmon.java:

1.packageanimals.fish;

2.

3.publicclassSalmonextendsFish{

4.voidconsume（）{/*dostuff*/}

5.}

Assume（假定）bothclassesaredefinedinthecorrectdirectoriesfortheftpackages,andthattheMammalclasscorrectlydefinesthefindSalmon（）method.Whichtwochangesallowthiscodetocompilecorrectly?

（Choosetwo.）

A.addpublictothestartofline4inSalmon.java

B.addpublictothestartofline4inGrizzlyBear.java

C.addimportanimals.mammals.*;atline2inSalmon.java

D.addimportanimals.fish.*;atline2inGrizzlyBear.java

E.addimportanimals.fish.Salmon.*;atline2inGrizzlyBear.java

F.addimportanimals.mammals.GrizzlyBear.*;atline2inSalmon.java

Answer:

AD调用不同包下的类，要先导入，方法权限要设置成public

Question19

Given:

10.packagecom.sun.scjp;

11.publicclassGeodetics{

12.publicstaticfinaldoubleDIAMETER=12756.32;//kilometers

13.}

Whichtwocorrectlyaccess（访问）theDIAMETERmemberoftheGeodeticsclass?

（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;}}

Answer:

ACb中不能静态导入类，c中静态导入类属性，正确，d访问错误很明显

Question20

Givenclassesdefinedintwodifferentfiles:

1.packageutil;

2.publicclassBitUtils{

3.privatestaticvoidprocess（byte[]b）{}

4.}

1.packageapp;

2.publicclassSomeApp{

3.publicstaticvoidmain（String[]args）{

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

5.//insertcodehere

6.}

7.}

Whatisrequired（必需的）atline5inclassSomeApptousetheprocessmethod

ofBitUtils?

A.process（bytes）;

B.BitUtils.process（bytes）;

C.app.BitUtils.process（bytes）;

D.util.BitUtils.process（bytes）;

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

F.SomeAppcannotusetheprocessmethodinBitUtils.

Answer:

F私有的，不能被访问

Question21

GivenaclassRepetition（重复）:

1.packageutils;

2.

3.publicclassRepetition{

4.publicstaticStringtwice（Strings）{returns+s;}

5.}

andgivenanotherclassDemo:

1.//insertcodehere

2.

3.publicclassDemo{

4.publicstaticvoidmain（String[]args）{

5.System.out.println（twice（"pizza"））;

6.}

7.}

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静态导入

Question22

Given:

1.packagetest;

2.

3.classTarget（目标）{

4.publicStringname="hello";

5.}

Whatcandirectly（直接的）accessandchangethevalueofthevariable（变量）name?

A.anyclas