java考试选择题ss本.docx

java考试选择题ss本.docx

《java考试选择题ss本.docx》由会员分享，可在线阅读，更多相关《java考试选择题ss本.docx（30页珍藏版）》请在冰豆网上搜索。

java考试选择题ss本

Readthequestionscarefully

Ihavetriedtomakethequestionsunambiguous（themeaningshouldbeobvious）,butmakesureyouhavereadwhatIhavewrittennotwhatyouthinkImighthavewritten.Thusifitsays"Classescanbedeclaredwiththeprivatemodifier",itmeansItispossibletodeclareaclasswiththeprivatemodifierandnotthatallclassesinallsituationscanbedeclaredasprivate.EachquestionmayhaveoneormorecorrectAnswers.

臧廷杰

Questions

Question1）

Whichofthefollowinglineswillcompilewithoutwarningorerror.

1）floatf=1.3;

2）charc="a";

3）byteb=257;

4）booleanb=null;

5）inti=10;

Question2）

Whatwillhappenifyoutrytocompileandrunthefollowingcode

publicclassMyClass{

publicstaticvoidmain（Stringarguments[]）{

amethod（arguments）;

}

publicvoidamethod（String[]arguments）{

System.out.println（arguments）;

System.out.println（arguments[1]）;

}

}

1）errorCan'tmakestaticreferencetovoidamethod.

2）errormethodmainnotcorrect

3）errorarraymustincludeparameter

4）amethodmustbedeclaredwithString

Becausemainisdefinedasstaticyouneedtocreateaninstanceoftheclassinordertocallanynon-staticmethods.

--------------------------------------------------------------------------------

Question3）

Whichofthefollowingwillcompilewithouterror

要先出现package

1）importjava.awt.*;

packageMypackage;

classMyclass{}

2）packageMyPackage;

importjava.awt.*;

classMyClass{}

3）/*Thisisacomment*/

packageMyPackage;

importjava.awt.*;

classMyClass{}

--------------------------------------------------------------------------------

臧廷杰

Question4）

Abytecanbeofwhatsize

1）-128to127

2）（-2power8）-1to2power8

3）-255to256

4）dependsontheparticularimplementationoftheJavaVirtualmachine

--------------------------------------------------------------------------------

Question5）

Whatwillbeprintedoutifthiscodeisrunwiththefollowingcommandline?

Javamyproggoodmorning;

publicclassmyprog{

publicstaticvoidmain（Stringargv[]）

{

System.out.println（argv[2]）;

}

}

1）myprog

2）good

3）morning

4）Exceptionraised:

"java.lang.ArrayIndexOutOfBoundsException:

2"

--------------------------------------------------------------------------------

Question6）

Whichofthefollowingarekeywordsorreserved（预定义）wordsinJava?

1）if

2）then

3）goto

4）while

5）case

--------------------------------------------------------------------------------

Question7）

Whichofthefollowingarelegalidentifiers（标识符）臧廷杰

1）2variable

2）variable2

3）_whatavariable

4）_3_

5）$anothervar

6）#myvar

--------------------------------------------------------------------------------

Question8）

Whatwillhappenwhenyoucompileandrunthefollowingcode?

publicclassMyClass{

staticinti;

publicstaticvoidmain（Stringargv[]）{

System.out.println（i）;

}

}

局部变量（在函数内部）必须先初始化，类级别的可以不初始化

Classlevelvariablesarealwaysinitialisedtodefaultvalues.Inthecaseofanintthiswillbe0.Methodlevelvariablesarenotgivendefaultvaluesandifyouattempttouseonebeforeithasbeeninitialiseditwillcausethe

ErrorVariableimaynothavebeeninitialized

1）ErrorVariableimaynothavebeeninitialized

2）null

3）1

4）0

--------------------------------------------------------------------------------

Question9）

Whatwillhappenifyoutrytocompileandrunthefollowingcode?

publicclassQ{

publicstaticvoidmain（Stringargv[]）{

intanar[]=newint[]{1,2,3};

System.out.println（anar[1]）;

}

}

1）1

2）Erroranarisreferencedbeforeitisinitialized

3）2

4）Error:

sizeofarraymustbedefined

--------------------------------------------------------------------------------

Question10）

Whatwillhappenifyoutrytocompileandrunthefollowingcode?

publicclassQ{

publicstaticvoidmain（Stringargv[]）{

intanar[]=newint[5];

System.out.println（anar[0]）;

}

}

1）Error:

anarisreferencedbeforeitisinitialized

2）null

3）0

4）5

--------------------------------------------------------------------------------

Question11）

Whatwillbetheresultofattemptingtocompileandrunthefollowingcode?

abstractclassMineBase{

abstractvoidamethod（）;

staticinti;

}

publicclassMineextendsMineBase{

publicstaticvoidmain（Stringargv[]）{

int[]ar=newint[5];

for（i=0;i

System.out.println（ar[i]）;

}

}

Anyclassderivedfromanabstractclassmusteitherdefinealloftheabstractmethodsorbedeclaredabstractitself.

1）asequenceof50'swillbeprinted

2）Error:

arisusedbeforeitisinitialized

3）ErrorMinemustbedeclaredabstract

4）IndexOutOfBoundesError

--------------------------------------------------------------------------------

Question12）

Whatwillbeprintedoutifyouattempttocompileandrunthefollowingcode?

inti=1;

switch（i）{

case0:

System.out.println（"zero"）;

break;

case1:

System.out.println（"one"）;

case2:

System.out.println（"two"）;

default:

System.out.println（"default"）;

}

1）one

2）one,default

3）one,two,default

4）default

--------------------------------------------------------------------------------

Question13）

Whatwillbeprintedoutifyouattempttocompileandrunthefollowingcode?

inti=9;

switch（i）{

default:

System.out.println（"default"）;

case0:

System.out.println（"zero"）;

break;

case1:

System.out.println（"one"）;

case2:

System.out.println（"two"）;

}

1）default

2）default,zero

3）errordefaultclausenotdefined

4）nooutputdisplayed

--------------------------------------------------------------------------------

Question14）

Whichofthefollowinglinesofcodewillcompilewithouterror

1）inti=0;

if（i）{

System.out.println（"Hello"）;

}

2）booleanb=true;

booleanb2=true;

if（b==b2）{

System.out.println（"Sotrue"）;

}

3）inti=1;

intj=2;

if（i==1||j==2）System.out.println（"OK"）;

4）inti=1;

intj=2;i

f（i==1&|j==2）System.out.println（"OK"）;

--------------------------------------------------------------------------------

Question15）

Whatwillbeoutputifyoutrytocompileandrunthefollowingcode,butthereis

nofilecalledHello.txtinthecurrentdirectory?

.

importjava.io.*;

publicclassMine{

publicstaticvoidmain（Stringargv[]）{

Minem=newMine（）;

System.out.println（m.amethod（））;

}

publicintamethod（）{

try{

FileInputStreamdis=newFileInputStream（"Hello.txt"）;

}catch（FileNotFoundExceptionfne）{

System.out.println（"Nosuchfilefound"）;

return-1;

}catch（IOExceptionioe）{}

finally{

System.out.println（"Doingfinally"）;

}

return0;

}

}

1）Nosuchfilefound

2Nosuchfilefound,-1

3）Nosuchfilefound,Doingfinally,-1

4）0

--------------------------------------------------------------------------------

Question16）

Whichofthefollowingstatementsaretrue?

1）Methodscannotbeoverridentobemoreprivate

2）staticmethodscannotbeoverloaded

Staticmethodscannotbeoverridenbuttheycanbeoverloaded

3）privatemethodscannotbeoverloaded

4）Anoverloadedmethodcannotthrowexceptionsnotcheckedinthebaseclass

--------------------------------------------------------------------------------

Question17）

Whatwillhappenifyouattempttocompileandrunthefollowingcode?

classBase{}

classSubextendsBase{}

classSub2extendsBase{}

publicclassCEx{

publicstaticvoidmain（Stringargv[]）{

Baseb=newBase（）;

Subs=（Sub）b;

}

}

1）Compileandrunwithouterror

2）CompiletimeException

3）RuntimeException

--------------------------------------------------------------------------------

Question18）

Whichofthefollowingstatementsaretrue?

1）System.out.println（-1>>>2）;willoutputaresultlargerthan10无符号右移

2）System.out.println（-1>>2）;willoutputapositivenumber输出-1

3）System.out.println（2>>1）;willoutputthenumber1

4）System.out.println（1<<<2）;willoutputthenumber4

--------------------------------------------------------------------------------

Question19）

Whatwillhappenwhenyouattempttocompileandrunthefollowingcode?

publicclassTuxextendsThread{

staticStringsName="vandeleur";

publicstaticvoidmain（Stringargv[]）{

Tuxt=newTux（）;

t.piggy（sName）;

System.out.println（sName）;

}

publicvoidpiggy（StringsName）{

sName=sName+"wiggy";

start（）;

}

publicvoidrun（）{

for（inti=0;i<4;i++）{

sName=sName+""+i;

}

}

}

1）Compiletimeerror

2）Compilationandoutputof"vandeleurwiggy"

3）Compilationandoutputof"vandeleurwiggy0123"

4）Compilationandoutputofeither"vandeleur","vandeleur0","vandeleur01""vandaleur012"or"vandaleur0123"

--------------------------------------------------------------------------------

Question20）

Whatwillbedisplayedwhenyouattempttocompileandrunthefollowingcode

//Codestart

importjava.awt.*;

publicclassButtextendsFrame{

publicstaticvoidmain（Stringargv[]）{

ButtMyBut=newButt（）;

}

Butt（）{

ButtonHelloBut=newButton（"Hello"）;

ButtonByeBut=newButton（"Bye"）;

add（HelloBut）;

add（ByeBut）;

setSize（300,300）;

setVisible（true）;}}//Codeend

1）Twobuttonssidebysideoccupyingalloftheframe,HelloontheleftandByeon

theright

2）OnebuttonoccupyingtheentireframesayingHello

3）OnebuttonoccupyingtheentireframesayingBye

4）TwobuttonsatthetopoftheframeonesayingHellotheothersayingBye

--------------------------------------------------------------------------------

Question21）

Whatwillbeoutputbythefollowingcode?

publicclassMyFor{

publicstaticvoidmain（Stringargv[]）