Java试题及答案英文版doc.docx
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Java试题及答案英文版doc
1・Whichtwodemonstrateanuisa”relationship?
（ChooseTwo）
A.publicinterfacePerson{}
publicclassEmployeeextendsPerson{}
B.publicinterfaceShape{}
publicclassEmployeeextendsShape{}
C.publicinterfaceColor{}
publicclassEmployeeextendsColor{}
D.publicclassSpecies{}
publicclassAnimal{privateSpeciesspecies;}
E.interfaceComporient{}
ClassContainerimplementsComponent（
PrivateComponent[]children;
Answer:
de
2.Given:
1.packagefoo;
2.
2.publicclassOuter（
3.publicstaticclassInner（
4.）
5.）
Whichstatementistrue?
A.AninstanceoftheInnerclasscanbeconstructedwith“newOuter」nner（）”
B.Aninstanceoftheinnerclasscannotbeconstructedoutsideofpackagefoo
C.Aninstanceoftheinnerclasscanonlybeconstructedfromwithintheouterclass
D.Fromwithinthepackagebar,aninstaneeoftheinnerclasscanbeconstructedwith“newinner（）n
Answer:
c
3.Exhibit：
1publicclassenclosinggone{
2publicclassinsideone{}
3}
4publicclassinertest{
5publicstaticvoidmain（Stringf]args）{
6enclosingoneeo=newenclosingone（）;
7//insertcodehere
8}
}
Whichstatementatline7constructsaninstanceoftheinnerclass?
A.InsideOneei=eo.newlnsideOne（）;
B.B.Eo」nsideOneei=eo.newInsideOne（）;
CInsideOneei=EnclosingOne.newInsideOne（）;
D.EnclosingOneInsideOneei=eo.newlnsideOne（）;
Answer:
a
C.4.
D.1）classSuper{
E.2）publicfloatgetNum（）{return3.Of;}
F・3）}
G.4）
H.5）publicclassSubextendsSuper{
I.6）
J・7）}
K.whichmethod,placedatline6,willcauseacompilererror?
L.A.publicfloatgetNum（）{return4.Of;}
M.B.publicvoidgetNum（）{}
N.C.publicvoidgetNum（doubled）{}
O.D.publicdoublegetNum（floatd）{return4.0d;}
Answer:
B
5.
1）publicclassFoo{
2）publicstaticvoidmain（Stringargs[]）{
3）try{return;}
4）finally!
System.out.println（^^Finally,,）;}
5）}
6）}
whatistheresult?
A.Theprogramrunsandprintsnothing.
B.Theprogramrunsandprints“Finally”.
C.Thecodecompiles,butanexceptionisthrownatruntime・
D.Thecodewillnotcompilebecausethecatchblockismissing.
Answer:
b
6・
//pointX
publicclassFoo{
publicstaticvoidmain（String[]args）{
PrintWriterout=newPrintWriter（new
java.io.OutputStreamWriter（System.out）,true）;
out.println（,,HelloH）;
}
}
whichstatementatpointXonline1allowsthiscodetocompileandrun?
A.importjava.io.PrintWriterB.ineludejava.io.Printwriter
C.importjava.io.OutputStreamWriterD.includejava.io.OutputStreamWriter
E.Nostatementisneeded
Answer:
a
6.whichthreearevaliddeclaractionofafloat?
A.floatfoo=-1;
B.floatfoo=1.0;
C.floatfoo=42e1;
D.floatfoo=2.02f;
E.floatfoo=3.03d;
F.floatfoo=0x0123;
Answer:
adf
8.
intindex=1;
intfoo[]=newint[3];
intbar=foo[index];
intbaz=bar+index;
whatistheresult?
A.bazhasavalueof0
B.bazhasvalueof1
C.bazhasvalueof2
D.anexceptionisthrown
E.thecodewillnotcompile
Answer:
b
9.
1）inti=1,j=10;
2）do{
3）if（i++>-j）continue;19283746
4）}while（i<5）;
AfterExecution,whatarethevalueforiandj?
A.i=6j=5
B.i=5j=5
C.i=6j=4
D.i=5j=6
E.i=6j=6
Answer:
d
10.
1）publicclassX{
2）publicObjectm（）{
3）Objecto=newFloat（3.14F）;
4）Object[]oa=newObject[1];
5）oa[0]=o;
6）o=null;
7）oa[0]=null;
8）System.out.println（oa[0]）;
9）}
10）}
whichlineistheearliestpointtheobjectareferedisdefinitelyelibiletobegarbagecollectioned?
A.Afterline4
B.Afterline5
C.Afterline6
D.Afterline7
E.Afterline9
Answer:
d
11.
1.publicclassX{
2.
publicstaticvoidmain（String[]args）{
3.
Objecto1=newObject（）;
4.
Objecto2=o1;
5.
if（o1.equals（o2））{
6.
System.out.println（”Equal”）；
7.
}
&
}
9.}
Whatistheresult?
A.Theprogramrunsandprintsnothing.
B.Theprogramrunsandprints“Equal”.
C.Anerroratline5causescompilationtofail.
D.Theprogramrunsbutabortswithanexception.
Answer:
B
12.
1）publicclassTest{
2）publicstaticvoidadd3（lntegeri）{
3）intval=i.intValue（）;
4）val+=3;
5）i=newInteger（val）;
6）}
7）publicstaticvoidmain（Stringargs[]）{
8）Integeri=newInteger（O）;
9）add3（i）;
10）System.out.println（i.intValue（））;
11）}
12）}
whatistheresult?
A.compilefail
B.printoutn0u
C.printoutM3n
D.compilesuccededbutexceptionatline3
Answer:
b
13.
Given:
1.publicclassFoo{
2.publicvoidmain（String[]args）{
3.system.out.printlnfHelloWorld.5,）;
4.}
5.}
Whatistheresult?
A.Anexceptionisthrown.
B.Thecodedoesnotcompile・
C.“HelloWorld.5,isprintedtotheterminal.
D.Theprogramexitswithoutprintinganything.
AnswerA
14.Given:
13.publicclassFoo{
14.publicstaticvoidmain（String[]args）{
15.StringBuffera=newStringBuffer（“A”）;
16.StringBufferb=newStringBuffer（“B”）;
17.operate（a,b）;
18.system.out.println{a+“,”+b};
19.）
20.staticvoidoperate（StringBufferx,StringBuffery）{
21.y.append（x）;
22.y=x;
23.）
24.}
Whatistheresult?
A.Thecodecompilesandprints
B.Thecodecompilesandprints“A,BA”.
C.Thecodecompilesandprints“AB,B”.
D.Thecodecompilesandprints“AB,AB”.
E.Thecodecompilesandprints“BA,BA”.
F.Thecodedoesnotcompilebecause“+”cannotbeoverloadedforstringBuffer.
AnswerB
15.
Given:
1・publicclassSyncTest{
2.privateintx;
3.privateinty;
4.publicsynchronizedvoidsetX（inti）（x=1;）
5.publicsynchronizedvoidsetY（inti）（y=1;）
6.publicsynchronizedvoidsetXY（int1）（setX（i）;setY（i）;）
7.publicsynchronizedBooleancheck（）（returnx!
=y;）
8.）
Underwhichconditionswillcheck（）returntruewhencalledfromadifferentclass?
A.Check（）canneverreturntrue・
B.Check（）canreturntruewhensetXYiscalledbymultiplethreads.
C.Check（）canreturntruewhenmultiplethreadscallsetXandsetYseparately.
D.Check（）canonlyreturntrueifSyncTestischangedtoallowxandytobesetseparately.
Answer:
A
16.
1）publicclassTest{
2）publicstaticvoidmain（String[]args）{
3）Stringfoo=args[1];
4）Sringbar=args[2];
5）Stringbaz=args[3];
6）}
7）}
javaTestRedGreenBlue
whatisthevalueofbaz?
A.bazhasvalueof””
B.bazhasvalueofnull
C.bazhasvalueof”Red”
D.bazhasvalueof”Blue”
E.bazhasvalueof”Green”
F.thecodedoesnotcompile
G.theprogramthrowanexception
Answer:
G
17.
1）interfaceFoo{
2）intk=0;
3）}
4）publicclassTestimplementsFoo{
5）publicstaticvoidmain（Stringargs[]）{
6）inti;
7）Testtest=newTest（）;
8）
i=test.k;
9）
i=Test.k;
10）
i=Foo.k;
11）
}
12）}
Whatistheresult?
A.Compilationsucceeds.
B.Anerroratline2causescompilationtofail.
C.Anerroratline9causescompilationtofail.
D.Anerroratline10causescompilationtofail.
E.Anerroratline11causescompilationtofail.Answer:
a
classBaseClass{
privatefloatx=1.Of;
privatefloatgetVar（）{returnx;}
}
classSubClassextendsBaseClass{
privatefloatx=2.0f;
//insertcode
}
whataretruetooverridegetVar（）?
A.floatgetVar（）{
B.publicfloatgetVar（）{
C.publicdoublegetVar（）{
□.protectedfloatgetVar（）{
E.publicfloatgetVar（floatf）{
Answer:
a,b,d
19.
Given:
inti=1,j=10;
do{
if（i>j）continue;
卜・；}while（++iv6）;
whatarethevaleofiandj?
A.i=6,j=5
B.i=5,j=5
C.i=6,j=4
D.i=5,j=6
E.i=6,j=6
Answer:
A
20・
byte[]arrayl,array2[]
bytearray3[][]
byte[][]array4
ifeachhasbeeninitialized,whichstatementwillcauseacompileerror?
A.array2=arrayl;
B.array2=array3;
C.array2=array4;
D.bothAandB
E.bothAandC
F.bothBandC
Answer:
a
21.
whichfourtypesofobjectscanbethrownuse”throws”？
A.Error
B.Event
C.Object
D.Excption
E.Throwable
F.RuntimeException
Answer:
A,D,E,F
22.
1）publicclassTest{
2）publicstaticvoidmain（String[]args）{
3）unsignedbyteb=0;
4）b-;
5）
5）}
6）}
whatisthevalueofbatline5?
A.-1B.255C.127D.compilefailE.compilesucceededbutrunerror
Answer:
d
23.
publicclassExceptionTest{
classTestExceptionextendsException{}
publicvoidrunTest（）throwsTestException{}
publicvoidtest（）/*pointx*/{
runTest（）;
}
}
Atpointx,whichcodecanbeaddontomakethecodecompile?
A.throwsException
B.catch（Exceptione）
C.throwsRuntimeException
D.catch（TestExceptione）
E.nocodeisnecessary
Answer:
A
24・
Stringfoo=”blue”；
boolean[]bar=newboolean[1];
if（bar[O]）{
foo=HgreenH;
whatisthevalueoffoo?
A.””B.nullC.blueD.green
Answer:
C
25.
whichtwoareequivalent?
A.3/2
B.3<2
C.3*4
D.3«2
E.3*2A2
F.3«<2
Answer:
c,d
26.
intindex=1;
String[]test=newString[3];
Stringfoo=test[index];
whatistheresultoffoo?
A.foohasthevalue“”
B.foohasthevaluenull
C.anexceptionisthrown
D.thecodewillnotcompile
Answer:
b
27.
whichtwoaretrue?
A.staticinnerclassrequiresastaticinitializer
B.Astaticinnerclassrequiresaninstaneeoftheenclosingclass
C.Astaticinnerclasshasnorefereneetoaninstanceoftheenclosingclass
D.Astaticinnerclasshasaccessstothenon・staticmemberoftheotherclass
E.staticmembersofastaticinnerclasscanberefereneedusingtheclassnameofthestaticinnerclass
Answer:
c,e
28.
Youwantsubclassesinanypackagetohaveaccesstomembersofasuperclass.Whichisthemostrestrictiveaccessmodifierthatwillaccomplishthisobjective?
A.Public
B.Private
C.Protected
D.Transient
E.Noaccessmodifierisqualified
Answer:
c
29.Given:
1.abstractclassabstrctlt{
2.abstractfloatgetFloat（）;
3.）
4.publicclassAbstractTestextendsAbstractly
5.privatefloatf1=1.0f;
6.privatefloatgetFloat（）{returnf1:
}
7・}
Whatistheresult?
A.Compilationissuccessful.
B.Anerroronline6causesaruntimefailure.
C.Anerroratline6causescompilationtofail.
D.Anerroratline2causescompilationtofail.
Ans
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