英文 SCJP 模拟题200道附答案.docx

英文 SCJP 模拟题200道附答案.docx

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英文SCJP模拟题200道附答案

SCJP模拟题200道附答案

Q1Whichofthefollowingstatementsarevalid,giventhefollowingvariabledeclarations:

booleana;booleanb;intc;

1）（a|b）

2）（a||a）

3）（a^b）|c

4）（a&c）

5）（a&&c）

Q2Whichofthefollowingcanbeappliedtoconstructors:

1）final

2）static

3）synchronized

4）native

5）Noneofthese.

Q3Whichofthefollowingretaintheirpreferredsize（widthandheight）whenadded（individually）totheNorthsectionofacontainerwithaBorderLayout（assumethatnoothercomponentsorcontainersarepresentintheNorthsection）.

1）TextArea

2）Button

3）TextField

4）Checkbox

5）None.Allofthesementionedcomponentswillonlyretaintheirpreferredheight.

Q4Whichofthefollowingarelegalnamesforvariables.

1）_int

2）%large

3）$fred

4）Integer

5）2much

Q5Whichofthefollowingarecorrectwaystocreateafont.

1）Fontf=newFont（"Serif",Font.BOLD,24）;

2）Fontf=newFont（Font.SERIF,"Bold",24）;

3）Fontf=newFont（"Serif","Bold",24）;

4）Fontf=newFont（Font.SERIF,Font.BOLD,24）;

Q6Selectthecorrectstatementsregardingthefollowingpieceofcode.

Filef=newFile（"c:

\\large.txt"）;

1）Onexecution,afilecalled"large.txt"willbecreatedonthelocalharddisk.

2）ThecodefailstocompileonaUNIXmachine,becausethedirectoryseparatorisnotcorrect.

3）AfileisNOTcreatedontheharddiskwhenthiscodeisexecuted.

4）Anexceptionisthrownatruntimeifthefile"large.txt"alreadyexists.

5）Thecodefailstocompile,sincethisisnotavalidconstructorfortheFileclass.

Q7WhichofthefollowingstatementsarecorrectregardingtheRandomAccessFileclass?

1）AnIOExceptionisthrownifthespecifiedfiledoesn'texistwhencreatedusingthe"r"mode.

2）Thisclasshasamethodwhichallowsafiletobedeletedfromtheharddisk.

3）ItispossibletousethisclassinconjunctionwiththeDataInputStreamclass.

4）Whenusedwiththe"rw"mode,thespecifiedfileiscreatedonadiskdrive,ifitdoesn'talreadyexist.

5）Therearemethodstoreadandwriteprimatives（eg,readInt（）,writeInt（）,etc）.

Q8Considerthefollowingpieceofcodeandselectthecorrectstatementfromthefollowing.

1.Strings=newString（"abcdefgh"）;

2.s.replace（'d','q'）;

3.System.out.println（s）;

1）Thecodefailstocompile,reportinganerroratline2.Stringsareimmutable,andthereforeareplace（）methodismeaningless.

2）Thecodecompilescorrectly,anddisplaysthetext"abcqefgh".

3）Thecodecompilescorrectly,anddisplaysthetext"abcdefgh".

4）Thecodecompiles,butanexceptionisthrownwhenline2isexecuted.

5）Thecodecompiles,butanexceptionisthrownatline3.

Q9Whichofthefollowingkeywordscanbeappliedtothevariablesormethodsofaninterface.

1）static

2）private

3）synchronised

4）protected

5）public

Q10TrueorFalse.

OnlyFramescancontainmenubarsorpull-downmenus.

1）True

2）False.

Q11Considerthefollowingpieceofcodeandselectthecorrectstatement（s）:

1.classA{

2.protectedintmethod（）{

3.}

4.}

5.

6.classBextendsA{

7.intmethod（）{

8.}

9.}

1）Thecodefailstocompile,becauseyoucan'toverrideamethodtobemoreprivatethanitsparent.

2）Thecodefailstocompile,becausemethod（）isdeclaredasprotected,andisthereforenotavailabletoanysubclass.

3）Thecodecompilescorrectly,butthrowsaNullPointerExceptionatruntime.

4）Thecodefailstocompile.However,itcanbemadetocompilecorrectlybyprefixingline7withtheaccessqualifier"public".

5）Thecodefailstocompile.However,itcanbemadetocompilecorrectlybyprefixingline7withtheaccessqualifier"protected".

Q12TrueorFalse.

TheThrowableclassisthesuperclassofallexceptionsintheJavalanguage.

1）True

2）False

Q13Considerthefollowingpieceofcode（assumetheGraphicscontextgisdefinedcorrectly）:

g.setBackground（Color.red）;

g.setForeground（Color.white）;

g.drawLine（10,10,50,10）;

g.setForeground（Color.blue）;

g.drawRect（100,100,50,50）;

Whatisdisplayedwhenthiscodeisexecuted.

1）Abluelinefrom（10,10）to（50,10）andabluerectanglewithupperleftcornerat（100,100）.

2）Awhitelinefrom（10,10）to（50,10）andabluesquarewithtopleftcornerat（100,100）.

3）Awhitelinefrom（10,10）to（10,50）andabluesquarewithlowerleftcornerat（100,100）.

4）Aredlinefrom（10,10）to（50,10）andaredsquarewithupperleftcornerat（100,100）.

5）Nothingisdisplayed.Youmustfirstissuearepaint（）command.

Q14Considerthefollowingpieceofcode.

classTest{

publicstaticvoidmain（String[]args）{

System.out.println（args[3]）;

}

}

Whenthefollowingistypedatthecommandline,whatisdisplayed:

javaTestMetallicaJusticeForAll

1）All

2）For

3）Justice

4）Nothing.

5）Nothing.AnArrayIndexOutOfBoundsExceptionisthrown

Q15Considerthefollowingpieceofcode.

1.Strings="abcd";

2.Integerx=newInteger（3）;

3.Strings2=s+4;

4.s2=null;

5.s=null;

Followingtheexecutionofwhichlineabove,istheobjectreferencedbys2availableforgarbagecollection.

1）Line5

2）Itisnotpossibletosaywhenanobjectisavailableforgarbagecollection.

3）Line4

4）Theobjectsarenotavailableuntiltheexecutingthreadisended.

Q16Whatisdisplayedwhenthefollowingpieceofcodeiscompiledandexecuted:

classTest{

publicstaticvoidmain（String[]args）{

Baseb=newSubclass（）;

System.out.println（b.x）;

System.out.println（b.method（））;

}

}

classBase{

intx=2;

intmethod（）{

returnx;

}

}

classSubclassextendsBase{

intx=3;

intmethod（）{

returnx;

}

}

1）Nothing.Thecodefailstocompilebecausetheobjectbisnotcreatedinavalidway.

2）2

3

3）2

2

4）3

3

5）3

2

Q17Whatisdisplayedwhenthefollowingisexecuted:

Strings1="aaa";

s1.concat（"bbb"）;

System.out.println（s1）;

1）Thestring"aaa".

2）Thestring"aaabbb".

3）Nothing.concat（）isnotavalidmethodintheStringclass.

4）Thestring"bbbaaa".

5）Thestring"bbb".

Q18TrueorFalse.

ThefollowingisavalidwaytoconstructaStringBuffer.

StringBuffersb1="abcd";

1）True

2）False

Q19Whatistheoutputofthefollowingpieceofcode:

1.intx=6;

2.doubled=7.7;

3.

4.System.out.println（（x>d）?

99.9:

9）;

1）9

2）9.0

3）99.9

4）Nothing.AnArithmeticExceptionisthrownatline4.

5）6

Q20Whichofthefollowingcanbeputinapplettags?

（selectallthecorrectanswers）

1）CODE

2）WIDTH

3）HEIGHT

4）PARAM

5）ARCHIVE

Q21Whatisprintedoutfollowingtheexecutionofthecodebelow:

1.classTest{

2.staticStrings;

3.publicstaticvoidmain（String[]args）{

4.intx=4;

5.if（x<4）

6.System.out.println（"Val="+x）;

7.else

8.System.out.println（s）;

9.}

10.}

Nothing.ThecodefailstocompilebecausetheStringsisn'tdeclaredcorrectly.

1）Thetext"Val=null"isdisplayed.

2）Thestring"Val="isdisplayed.

3）Thetext"null"isdisplayed.

4）Ablanklineoftextisprinted.

Q22TrueorFalse.

TheStringBufferclassdoesnothaveaconcat（）method.

1）True

2）False

Q23Whatisdisplayedwhenthefollowingpieceofcodeisexecuted（assumethegraphicscontext,g,iscorrectlysetup）:

g.drawString（"abc",10,10）;

1）Thetext"abc"withthelowerleftpartof"a"locatedatx=10,y=10.

2）Thetext"abc"withtheupperleftpartof"a"locatedatx=10,y=10.

3）Nothing.Thisisnotavalidmethod.

Q24TrueorFalse.

Anonymousclassescannothaveconstructors.

1）True

2）False

Q25ToreferenceaJARfromawebpage,whichofthefollowingkeywordsareused:

1）jar

2）class

3）zip

4）archive

5）package

Q26

Analysethefollowing2classesandselectthecorrectstatements.

classA{

privateintx=0;

staticinty=1;

protectedintq=2;

}

classBextendsA{

voidmethod（）{

System.out.println（x）;

System.out.println（y）;

System.out.println（q）;

}

}

1）ThecodefailstocompilebecausethevariablexisnotavailabletoclassB.

2）Thecodecompilescorrectly,andthefollowingisdisplayed:

012

3）Thecodefailstocompilebecauseyoucan'tsubclassaclasswithprivatevariables.

4）Removingtheline"System.out.println（x）"willallowthecodetocompilecorrectly.

5）ThecompilerwillcomplainthatthevariablexinclassBisundefined.

Q27Whichofthefollowinginterfacescanbeusedtomanageacollectionofelements,withnoduplication.

1）List

2）Vector

3）Set

Q28Whichofthefollowingstatementsaretrueregardinginnerclasses.

1）Variablesdefinedinsideinnerclassescannotbestatic.

2）Variablesdefinedinsideinnerclassescannotbestaticunlesstheinnerclassitselfisstatic.

3）Non-staticinnerclasses（whicharenotdefinedinamethod）haveaccesstoallclassandinstancevariables,regardlessoftheaccessqualifierofthosevariables.

4）Aninnerclasscanactuallybeasubclassoftheouterclass

5）Innerclassescanbedeclaredasprivate.Toplevel,outerclassescannot.

Q29Whichofthefollowingarevalidwaystodefineanabstractmethod.

1）abstractvoidTest（）;

2）abstractvoidTest（）{}

3）staticabstractvoidTest（）;

4）finalabstractvoidTest（）;

5）Methodscannotbedefinedasabstract,onlyvariablescanbeabstract.

Q30Considerthefollowing:

classAextendsInteger{

intx=0;

}

Selectallvalidstatements.

1）Thecodewillcompilecorrectly.

2）ThecodewillnotcompilebecauseIntegerisfinalandcannotbesubclassed.

3）ThecodewillnotcompilebecauseclassAhasnomethodsorconstructor.

4）Thecodewillcompile