JAVA练习题

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ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶1'1⚪isanobject-orientedprogramminglanguage.1ஹJava2ஹC++3ஹC4ஹAda5ஹPascal'2⚪isArchitecture-Neutral.1ஹJava2ஹC++3ஹC4ஹAda5ஹPascal'3⚪isatechnicaldefinitionofthelanguagethatincludesthesyntaxandsemanticsoftheJavaprogramminglanguage.1ஹJavalanguagespecification2ஹJavaAPI3^JavaJDK4ஹJavaIDE'4⚪consistsofasetofseparateprogramsfordevelopingandtestingJavaprograms,eachofwhichisinvokedfromacommandline.1ஹJavalanguagespecification2ஹJavaAPI3ஹJavaJDK4ஹJavaIDE'5⚪providesanintegrateddevelopmentenvironment(IDE)forrapidlydevelopingJavaprograms.Editing,compiling,building,debugging,andonlinehelpareintegratedinonegraphicaluserinterface.1ஹJavalanguagespecification2ஹJavaAPI3ஹJavaJDK4ஹJavaIDE'6⚪Themainmethodheaderiswrittenas:1ஹpublicstaticvoidmain(string[]args)2ஹpublicstaticvoidMain(String[]args)3ஹpublicstaticvoidmain(String[]args)4ஹpublicstaticmain(String[]args)5ஹpublicvoidmain(String[]args)'7⚪Whichofthefollowingstatementsiscorrect?1ஹEverylineinaprogrammustendwithasemicolon.2ஹEverystatementinaprogrammustendwithasemicolon.3ஹEverycommentlinemustendwithasemicolon;4ஹEverymethodmustendwithasemicolon;

15^Everyclassmustendwithasemicolon;
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶2'8⚪WhichofthefollowingstatementsiscorrecttodisplayWelcometoJavaontheconsole?1ஹSystem.out.println(WelcometoJava);2ஹSystem.out.printlnC'WelcometoJava'*);3ஹSystem.println(WelcometoJava);4ஹSystem.out.print(WelcometoJava);5ஹSystem.out.print(nWelcometoJava'');'9⚪WhichJDKcommandiscorrecttorunaJavaapplicationinByteCode.class?1ஹjavaByteCode2ஹjavaByteCode.class3ஹjavacByteCode.java4ஹjavacByteCode5ஹJAVACByteCode'10⚪SupposeyoudefineaJavaclassasfollows:publicclassTest{}Inordertocompilethisprogram,thesourcecodeshouldbestoredinafilenamed1ஹTest.class2ஹTest.doc3ஹTest.txt4ஹTest.java5ஹAnynamewithextension.java'11⚪TheextensionnameofaJavabytecodefileis1ஹ.java2ஹ.obj3ஹ.class4ஹ.exe'12⚪WhichofthefollowinglinesisnotaJavacomment?1ஹ/**comments*/2ஹ//comments3^-comments4ஹ/*comments*/5^**comments**'13⚪Whichofthefollowingarethereservedwords?1ஹpublic2ஹstatic3ஹvoid4ஹclass'14⚪TouseJOptionPaneinyourprogram,youmayimportitusing:

21ஹimportjavax.swing.JOptionPane;2ஹimportjavax.swing.*;3^importjavax.*;
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶34ஹimportjavax/.JOptionPane;'15⚪WhichofthefollowingarecorrectnamesforvariablesaccordingtoJavanamingconventions?1ஹradius2ஹRadius3ஹRADIUS4ஹfindArea5ஹFindArea'16⚪Whichofthefollowingarecorrectwaystodeclarevariables?1ஹintlength;intwidth;2>intlength,width;3^intlength;width;4ஹintlength,intwidth;'17⚪istheJavaassignmentoperator.1ஹ==2ஹ:=3ஹ=4ஹ=:'18⚪Whichofthefollowingassignmentstatementsisincorrect.1ஹi=j=k=1;2ஹi=1;j=1;k=1;3>i=1=j=1=k=1;4ஹi==j==k==1;/19⚪Whichofthefollowingisaconstant,accordingtoJavanamingconventions?1ஹMAX_VALUE2ஹTest3ஹread4ஹReadlnt5ஹCOUNT'20⚪Todeclareanintvariablenumberwithinitialvalue2,youwrite1ஹintnumber=2L;2ஹintnumber=2I;3ஹintnumber=2;4ஹintnumber=2.0;/21⚪Whichofthefollowingexpressionswillyield0.5?1ஹ1/22ஹ1.0/23ஹ(double)(1/2)

34ஹ(double)1/25ஹ1/2.0'22⚪Whichofthefollowingexpressionresultsinavalue1?1ஹ2%12ஹ15%4
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶43ஹ25%54ஹ37%6'23⚪25%5is1ஹ12ஹ23ஹ34ஹ45ஹ0'24⚪24%5is1ஹ32ஹ-33ஹ44ஹ-45ஹ0'25®iToaddnumbertosum,youwrite(Note:Javaiscase-sensitive)1ஹnumber+=sum;2ஹnumber=sum+number;3ஹsum=Number+sum;4ஹsum+=number;5ஹsum=sum+number;'26⚪Supposexis1.Whatisxafterx-=1?1ஹ02ஹ13ஹ24ஹ-15ஹ-2'270iWhatisxafterthefollowingstatements?intx=1;inty=2;x*=y+1;1ஹxis1;2ஹxis2;3ஹxis3;4ஹxis4;'28⎀Whatisydisplayed?publicclassTest{publicstaticvoidmain(String[]args){

4intx=1;inty=x+x++;System.out.println(Myis"+y);}}1ஹyis1.2ஹyis2.
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶53ஹyis3.4ஹyis4.'29⚪Whatisydisplayedinthefollowingcode?publicclassTest{publicstaticvoidmain(String[]args){intx=1;inty=x+++x;System.out.println("yis"+y);}}1ஹyis1.2ஹyis2.3ஹyis3.4ஹyis4.'30⚪Whatistheprintoutofthefollowingcode:doublex=5.5;inty=(int)x;System.out.println("xis"+x+Mandyis"+y);1ஹxis5andyis62ஹxis6.0andyis6.03ஹxis6andyis64ஹxis5.5andyis55ஹxis5.5andyis5.0'31⚪Supposexisacharvariablewithavalueb.WhatistheprintoutofthestatementSystem.out.println(++x)?1ஹa2ஹb3ஹc4ஹd'32⚪Supposeiisaninttypevariable.WhichofthefollowingstatementsdisplaythecharacterwhoseUnicodeisstoredinvariablei?1ஹSystem.out.println(i);2ஹSystem.out.println((char)i);3ஹSystem.out.println((int)i);4ஹSystem.out.println(i+"

5'33⚪Thefollowingcodefragmentreadsintwonumbers:Scannerinput=newScanner(System.in);inti=input.nextlntO;doubled=input.nextDouble();Whatarethecorrectwaystoenterthesetwonumbers?1ஹEnteraninteger,aspace,adoublevalue,andthentheEnterkey.2ஹEnteraninteger,twospaces,adoublevalue,andthentheEnterkey.3ஹEnteraninteger,anEnterkey,adoublevalue,andthentheEnterkey.
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶64ஹEnteranumericvaluewithadecimalpoint,aspace,aninteger,andthentheEnterkey.'34⚪Ifyouenter123,whenyourunthisprogram,whatwillbetheoutput?importjava.util.Scanner;publicclassTesti{publicstaticvoidmain(StringQargs){Scannerinput=newScanner(System.in);System.out.print(MEnterthreenumbers:”)4doublenumberl=input.nextDouble();doublenumber2=input.nextDouble();doublenumbers=input.nextDouble();//Computeaveragedoubleaverage=(numberl+number2+numbers)/3;//DisplayresultSystem.out.println(average);)}1ஹ1.02ஹ2.03ஹ3.04ஹ4.0'35⚪Theexpression(int)(76.0252175*100)/100evaluatesto1ஹ76.022ஹ763ஹ76.02521754ஹ76.03/36⚪AccordingtoJavanamingconvention,whichofthefollowingnamescanbevariables?1ஹFindArea2ஹfindArea3ஹtotalLength4ஹTOTAL_LENGTH

65^class'37⚪Themethoddisplaysaninputdialogforreadingastring.1ஹStringstring=JOptionPane.showMessageDialog(null,MEnterastring”,'InputDemo",JOptionPane.QUESTION_MESSAGE);2ஹStringstring=JOptionPane.showlnputDialog(null,"Enterastring",'InputDemo",JOptionPane.QUESTION_MESSAGE);3ஹStringstring=JOptionPane.showlnputDialog(HEnterastring1*,"InputDemo",JOptionPane.QUESTION_MESSAGE);4ஹStringstring=JOptionPane.showlnputDialog(null,"Enterastring*');
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶75ஹStringstring=JOptionPane.showlnputDialog("Enterastring");'38⚪Analyzethefollowingcode.importjavax.swing.*;publicclassShowErrors{publicstaticvoidmain(String[]args){inti;intj;Strings=JOptionPane.showlnputDialog(null,"Enteraninteger",''Input'',JOptionPane.QUESTION_MESSAGE);j=Integer.parselnt(s);i=(i+4);))1ஹTheprogramcannotcompilebecausejisnotinitialized.2ஹTheprogramcannotcompilebecauseidoesnothaveaninitialvaluewhenitisusedini=i+4;3ஹTheprogramcompilesbuthasaruntimeerrorbecauseidoesnothaveaninitialvaluewhenitisusedini=i+4;4ஹTheprogramcompilesandrunsfine.'39⚪Supposex=10andy=10.Whatisxafterevaluatingtheexpression(y>10)&&(x->10)?1ஹ92ஹ103ஹ11'40⚪Supposex=10andy=10whatisxafterevaluatingtheexpression(y>=10)||(x++>10).1ஹ92ஹ103ஹ11/41⚪Supposex=1,y=-1,andz=1.Whatistheprintoutofthefollowingstatement?(Pleaseindentthestatementcorrectlyfirst.)

7if(x>0)if(y>0)System.out.println(Mx>0andy>0");elseif(z>0)System.out.printing*<0andz>0");1>x>0andy>0;2>x<0andz>0;3>x<0andz<0;4ஹnoprintout.'42⚪Analyzethefollowingcode.booleaneven=false;if(even){
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶8System.out.println("ltiseven!*');}1ஹThecodedisplaysItiseven!2ஹThecodedisplaysnothing.3^Thecodeiswrong.Youshouldreplaceif(even)withif(even==true)4ஹThecodeiswrong.Youshouldreplaceif(even)withif(even=true)'43⚪Thefollowingcodedisplays.doubletemperature=50;if(temperature>=100)System.out.println(Mtoohot*');elseif(temperature<=40)System.out.println("toocold*');elseSystem.out.println(Mjustright**);1ஹtoohot2ஹtoocold3ஹjustright4ஹtoohottoocoldjustright'44⚪Analyzethefollowingcode:Code1:booleaneven;if(number%2==0)even=true;elseeven=false;Code2:booleaneven=(number%2==0);1ஹCode1hascompileerrors.2ஹCode2hascompileerrors.3ஹBothCode1andCode2havecompileerrors.

84ஹBothCode1andCode2arecorrect,butCode2isbetter.'45⚪Themethodimmediatelyterminatestheprogram.1ஹSystem.terminate(O);2ஹSystem.halt(O);3ஹSystem.exit(O);4ஹSystem.stop(O);'46⚪Whatistheprintoutofthefollowingswitchstatement?charch=a;switch(ch){casea:caseA:System.out.print(ch);break;caseb:caseB:
ᩈᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶9System.out.print(ch);break;casec:caseC:System.out.print(ch);break;cased:caseD:System.out.print(ch);}1ஹabed2ஹa3ஹaa4ஹab5ஹabc'47⚪Whatistheprintoutofthefollowingswitchstatement?charch=b;switch(ch){casea:System.out.print(ch);caseb:System.out.print(ch);casec:System.out.print(ch);cased:System.out.print(ch);)1ஹabed2ஹbed3ஹb

94ஹbb5ஹbbb'48⚪Analyzethefollowingprogramfragment:intx;doubled=1.5;switch(d){case1.0:x=1;case1.5:x=2;case2.0:x=3;}1ஹTheprogramhasacompileerrorbecausetherequiredbreakstatementismissingintheswitchstatement.2ஹTheprogramhasacompileerrorbecausetherequireddefaultcaseismissingintheswitchstatement.3ஹTheswitchcontrolvariablecannotbedouble.4ஹNoerrors.
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶10'49⚪Analyzethefollowingcodefragmentsthatassignabooleanvaluetothevariableeven.Code1:if(number%2==0)even=true;elseeven=false;Code2:even=(number%2==0)?true:false;Code3:even=number%2==0;1ஹCode2hasacompileerror,becauseyoucannothavetrueandfalseliteralsintheconditionalexpression.2ஹCode3hasacompileerror,becauseyouattempttoassignnumbertoeven.3ஹAllthreearecorrect,butCode1ispreferred.4ஹAllthreearecorrect,butCode2ispreferred.5^Allthreearecorrect,butCode3ispreferred./50⚪ThestatementSystem.out.printf(,'%3.1e",1234.56)outputs1ஹ0.1e+042ஹ0.123456e+043ஹ0.123e+044ஹ1.2e+035ஹ1.23+03'51⚪Analyzethefollowingcode:

10inti=3434;doubled=3434;System.out.printf(M%5.1f%5.1fM,i,d);1ஹThecodecompilesandrunsfinetodisplay3434.03434.0.2ஹThecodecompilesandrunsfinetodisplay34343434.0.3ஹiisaninteger,buttheformatspecifier%5.1fspecifiesaformatfordoublevalue.Thecodehasanerror.'52⚪Whatisthevalueofthefollowingexpression?true||true&&false1ஹtrue2ஹfalse'53⚪Whichofthefollowingstatementsaretrue?1ஹ(x>0&&x<10)issameas((x>0)&&(x<10))2ஹ(x>0||x<10)issameas((x>0)||(x<10))3ஹ(x>0||x<10&&y<0)issameas(x>0||(x<10&&y<0))4ஹ(x>0||x<10&&y<0)issameas((x>0||x<10)&&y<0)'54⚪Howmanytimeswillthefollowingcodeprint"WelcometoJava"?intcount=0;while(count<10){
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶11System.out.println(MWelcometoJava");count++;)1ஹ82ஹ93ஹ104ஹ115ஹ0'55⚪Analyzethefollowingcode.intcount=0;while(count<100){//PointASystem.out.println(nWelcometoJava!**);count++;//PointB}//PointC1ஹcount<100isalwaystrueatPointA2ஹcount<100isalwaystrueatPointB3^count<100isalwaysfalseatPointB4ஹcount<100isalwaystrueatPointC5ஹcount<100isalwaysfalseatPointC/56⚪HowmanytimeswillthefollowingcodeprintnWelcometoJava',?intcount=0;

11do{System.out.println(MWelcometoJava1,);}while(count++<10);1ஹ82ஹ93ஹ104ஹ115ஹ0'57⚪Whatisthevalueincountafterthefollowingloopisexecuted?intcount=0;do{System.out.println(MWelcometoJava");}while(count++<9);System.out.println(count);1ஹ82ஹ93ஹ104ஹ115ஹ0
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶12'58⚪Dothefollowingtwostatementsin(I)and(II)resultinthesamevalueinsum?(I)for(inti=0;i<10;++i){sum+=i;)(IDfor(inti=0;i<10;i++){sum+=i;)1ஹYes2ஹNo'59⚪Isthefollowingloopcorrect?for(;;);1ஹYes2ஹNo'60⚪Analyzethefollowingcode:publicclassTest{publicstaticvoidmain(Stringargs[]){inti=0;for(i=0;i<10;i++);System.out.println(i+4);}

121ஹTheprogramhasacompileerrorbecauseofthesemicolon(;)ontheforloopline.2ஹTheprogramcompilesdespitethesemicolon(;)ontheforloopline,anddisplays4.3ஹTheprogramcompilesdespitethesemicolon(;)ontheforloopline,anddisplays14.4ஹTheforloopinthisprogramissameasfor(i=0;i<10;i++){};System.out.println(i+4);'61⚪Toadd0.01+0.02+...+1.00,whatordershouldyouusetoaddthenumberstogetbetteraccuracy?1ஹadd0.01,0.02,1.00inthisordertoasumvariablewhoseinitialvalueis0.2ஹadd1.00,0.99,0.98,0.02,0.01inthisordertoasumvariablewhoseinitialvalueis0.'62⚪Whatissumafterthefollowingloopterminates?intsum=0;intitem=0;do{item++;sum+=item;
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶13if(sum>4)break;)while(item<5);1ஹ52ஹ63ஹ74ஹ8/63⚪Afterthecontinueouterstatementisexecutedinthefollowingloop,whichstatementisexecuted?outer:for(inti=1;i<10;i++){inner:for(intj=1;j<10;j++){if(i*j>50)continueouter;System.out.println(i*j);})next:1ஹThecontrolisintheouterloop,andthenextiterationoftheouterloopisexecuted.

132^Thecontrolisintheinnerloop,andthenextiterationoftheinnerloopisexecuted.3^Thestatementlabelednext.4ஹTheprogramterminates.'64⚪Supposetheinputfornumberis9.Whatistheoutputfromrunningthefollowingprogram?importjava.util.Scanner;publicclassTest{publicstaticvoidmain(String[]args){Scannerinput=newScanner(System.in);System.out.print("Enteraninteger:intnumber=input.nextlnt();inti;booleanisPrime=true;for(i=2;iiis3followedby9isnotprime3>iis4followedby9isprime4ஹiis4followedby9isnotprime'65⚪Supposeyourmethoddoesnotreturnanyvalue,whichofthefollowingkeywordscanbeusedasareturntype?1ஹvoid2>int3ஹdouble4ஹpublic5ஹNoneoftheabove'66⚪AllJavaapplicationsmusthaveamethod.1ஹpublicstaticMain(String[]args)2ஹpublicstaticMain(Stringargs[])3ஹpublicstaticvoidmain(String[]args)4ஹpublicvoidmain(String[]args)

145ஹpublicstaticmain(String[]args)'67⚪Doesthereturnstatementinthefollowingmethodcausecompileerrors?publicstaticvoidmain(String[]args){intmax=0;if(max!=0)System.out.println(max);elsereturn;}1ஹYes2ஹNo'68⚪Doesthemethodcallinthefollowingmethodcausecompileerrors?publicstaticvoidmain(String[]args){Math.pow(2,4);}1ஹYes2ஹNo'69⚪SupposestaticvoidnPrint(Stringmessage,intn){while(n>0){System.out.print(message);n-4}
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶15)WhatistheprintoutofthecallnPrint(a,4)?1ஹaaaaa2ஹaaaa3ஹaaa4ஹinvalidcall'70⚪SupposestaticvoidnPrint(Stringmessage,intn){while(n>0){System.out.print(message);n-4}}WhatiskafterinvokingnPrint(MAmessage'1,k)?intk=2;nPrint(MAmessage1*,k);1ஹ02ஹ1

153ஹ24ஹ3'71⚪Analyzethefollowingcode:publicclassTest{publicstaticvoidmain(String[]args){System.out.println(xMethod(5,500L));}publicstaticintxMethod(intn,longI){System.out.println(Mint,long*');returnn;}publicstaticlongxMethod(longn,longI){System.out.printlnt^long,long");returnn;}}1ஹTheprogramdisplaysint,longfollowedby5.2ஹTheprogramdisplayslong,longfollowedby5.3^Theprogramrunsfinebutdisplaysthingsotherthan5.4ஹTheprogramdoesnotcompilebecausethecompilercannotdistinguishwhichxmethodtoinvoke.'72⚪Analyzethefollowingcode.publicclassTest{publicstaticvoidmain(String[]args){System.out.println(max(1,2));)
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶16publicstaticdoublemax(intnum1,doublenum2){System.out.println(Hmax(int,double)isinvoked0);if(num1>num2)returnnum1;elsereturnnum2;}publicstaticdoublemax(doublenum1,intnum2){System.out.println(Mmax(double,int)isinvoked11)4if(num1>num2)returnnum1;elsereturnnum2;))1ஹTheprogramcannotcompilebecauseyoucannothavetheprint

16statementinanon-voidmethod.2ஹTheprogramcannotcompilebecausethecompilercannotdeterminewhichmaxmethodshouldbeinvoked.3ஹTheprogramrunsandprints2followedbyMmax(int,double)"isinvoked.4ஹTheprogramrunsandprints2followedby"max(double,int)"isinvoked.5ஹTheprogramrunsandprints“max(int,double)isinvoked*,followedby2.'73ḸTheclientcanuseamethodwithoutknowinghowitisimplemented.Thedetailsoftheimplementationareencapsulatedinthemethodandhiddenfromtheclientwhoinvokesthemethod.Thisisknownas1ஹinformationhiding2ஹencapsulation3ஹmethodhiding4ஹsimplifyingmethod'74ᓽWhatisMath.floor(3.6)?1ஹ3.02ஹ33ஹ44ஹ5.0'75⚪Ifyoudeclareanarraydouble8list={3.4,2.0,3.5,5.5},list[1]is1ஹ3.42ஹ2.03ஹ3.44ஹ5.55ஹundefined
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶17'76⚪Ifyoudeclareanarraydouble8list={3.4,2.0,3.5,5.5},thehighestindexinarraylistis.e,41ஹ02ஹ13ஹ24ஹ3'77⚪Supposeinti=5,whichofthefollowingcanbeusedasanindexforarraydoubledt=newdouble[100]?1ஹi2ஹ(int)(Math.random()*100))3ஹi+104>i+6.55ஹMath.random()*100'78⚪Analyzethefollowingcode.publicclassTest{

17publicstaticvoidmain(String[]args){intox=newint[3];System.out.println(Mx[0]is"+x[0]);}}1ஹTheprogramhasacompileerrorbecausethesizeofthearraywasntspecifiedwhendeclaringthearray.2ஹTheprogramhasaruntimeerrorbecausethearrayelementsarenotinitialized.3ஹTheprogramrunsfineanddisplaysx[0]is0.4ஹTheprogramhasaruntimeerrorbecausethearrayelementx[0]isnotdefined.'79⚪Whatwouldbetheresultofattemptingtocompileandrunthefollowingcode?publicclassTest{publicstaticvoidmain(String[]args){doubledx=newdouble[]{1,2,3};System.out.println(HValueis"+x[1]);})1ஹTheprogramhasacompileerrorbecausethesyntaxnewdouble[]{1,2,3}iswronganditshouldbereplacedby{1,2,3).2ஹTheprogramhasacompileerrorbecausethesyntaxnewdouble[]{1,2,3}iswronganditshouldbereplacedbynewdouble[3]{1,2,3};3^Theprogramhasacompileerrorbecausethesyntaxnewdouble[]{1,2,3}iswronganditshouldbereplacedbynewdouble[]{1.0,2.0,3.0};4ஹTheprogramcompilesandrunsfineandtheoutput"Valueis1.0"isprinted.
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶185ஹTheprogramcompilesandrunsfineandtheoutput"Valueis2.0"isprinted.'80⚪Analyzethefollowingcode:publicclassTest{publicstaticvoidmain(StringQargs){intQx=newint[5];inti;for(i=0;i

183^TheprogramhasaruntimeerrorbecausethelaststatementinthemainmethodcausesArraylndexOutOfBoundsException.4ஹTheprogramhasacompileerrorbecauseiisnotdefinedinthelaststatementinthemainmethod.'81⚪Inthefollowingcode,whatistheprintoutforIist2?classTest{publicstaticvoidmain(String[]args){intolistl={1,2,3};intoIist2={1,2,3};Iist2=listl;listl[0]=0;listl[1]=1;Iist2[2]=2;for(inti=0;i

19}1ஹTheprogramdisplays12342ஹTheprogramdisplays003ஹTheprogramdisplays00344ஹTheprogramdisplays0000'84⚪Analyzethefollowingcode:publicclassTest{publicstaticvoidmain(String[]args){finalint[]x={1,2,3,4};intQy=x;x=newint[2];for(inti=0;i

20publicstaticvoidincrease(int[]x){for(inti=0;i224ஹ215ஹ12'87⚪Dothefollowingtwoprogramsproducethesameresult?ProgramI:publicclassTest{publicstaticvoidmain(String[]args){intQlist={1,2,3,4,5);reverse(list);for(inti=0;i

21list=newList;}}1ஹYes2ஹNo'88⚪Analyzethefollowingcode:publicclassTesti{publicstaticvoidmain(String[]args){xMethod(newdouble[]{3,3});xMethod(newdouble[5]);xMethod(newdouble[3]{1}2,3});)publicstaticvoidxMethod(double[]a){System.out.println(a.length);}}1ஹTheprogramhasacompileerrorbecausexMethod(newdouble[]{3,3})isincorrect.2ஹTheprogramhasacompileerrorbecausexMethod(newdouble[5])isincorrect.3ஹTheprogramhasacompileerrorbecausexMethod(newdouble[3]{1,2,3})isincorrect.4ஹTheprogramhasaruntimeerrorbecauseaisnull.'89⚪Thereversemethodisdefinedinthetextbook.Whatislistlafterexecutingthefollowingstatements?intolistl={1,2,3,4,5,6);listl=reverse(listl);1>listlis1234562ஹlistlis6543213ஹlistlis0000004.listlis666666'90⚪ForthebinarySearchmethodinSection6.7.2,whatislowandhighafterthefirstiterationofthewhileloopwheninvokingbinarySearch(newint0{1,4,6,8,10,15,20},11)?1ஹlowis0andhighis62>lowis0andhighis3
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶223>lowis3andhighis64ஹlowis4andhighis65ஹlowis0andhighis5'91⚪TheselectionSortmethodisdefinedinthissection.Whatislistlafterexecutingthefollowingstatements?doubledlistl={3,1,3.1,2.5,6.4};

22selectionSort(list1);1ஹlistlis3.1,3.1,2.5,6.42ஹlistlis2.53.1,3.1,6.43ஹlistlis6.4,3.1,3.1,2.54ஹlistlis3.1,2.5,3.1,6.4'92⚪Analyzethefollowingcode:publicclassTest{publicstaticvoidmain(String[]args){boolean88x=newboolean[3][];x[0]=newboolean[1];x[1]=newboolean[2];x[2]=newboolean[3];System.out.println("x[2][2]is"+x[2][2]);)}1ஹTheprogramhasacompileerrorbecausenewboolean[3][]iswrong.2ஹTheprogramhasaruntimeerrorbecausex[2][2]isnull.3^Theprogramrunsanddisplaysx[2][2]isnull.4ஹTheprogramrunsanddisplaysx[2][2]istrue.5ஹTheprogramrunsanddisplaysx[2][2]isfalse.'93⚪isaconstructthatdefinesobjectsofthesametype.1ஹAclass2ஹAnobject3ஹAmethod4ஹAdatafield'94⚪Anobjectisaninstanceofa.1ஹprogram2ஹclass3ஹmethod4ஹdata'95⚪Thekeywordisrequiredtodeclareaclass.1ஹpublic2ஹprivate3^class4ஹAlloftheabove.'96⚪Whichofthefollowingstatementsaretrue?1ஹAdefaultno-argconstructorisprovidedautomaticallyifnoconstructorsareexplicitlydeclaredintheclass.2ஹAtleastoneconstructormustalwaysbedefinedexplicitly.
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶233ஹConstructorsdonothaveareturntype,notevenvoid.4ஹConstructorsmusthavethesamenameastheclassitself.5ஹConstructorsareinvokedusingthenewoperatorwhenanobjectiscreated.

23'97⚪Analyzethefollowingcode:publicclassTest{publicstaticvoidmain(String[]args){Aa=newA();a.print();}}classA{Strings;A(Strings){this.s=s;)voidprint(){System.out.println(s);}}1ஹTheprogramhasacompilationerrorbecauseclassAisnotapublicclass.2ஹTheprogramhasacompilationerrorbecauseclassAdoesnothaveadefaultconstructor.3ஹTheprogramcompilesandrunsfineandprintsnothing.4ஹTheprogramwouldcompileandrunifyouchangeAa=newA()toAa=newA("5").'98⚪Whatiswronginthefollowingcode?classTempCIass{inti;publicvoidTempClass(intj){inti=j;})publicclassC{publicstaticvoidmain(String[]args){TempCIasstemp=newTempClass(2);}}1ஹTheprogramhasacompilationerrorbecauseTempCIassdoesnothaveadefaultconstructor.2ஹTheprogramhasacompilationerrorbecauseTempCIassdoesnothaveaconstructorwithanintargument.3ஹTheprogramcompilesfine,butitdoesnotrunbecauseclassCisnotpublic.
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶244ஹTheprogramcompilesandrunsfine.'99⚪Analyzethefollowingcode.

24publicclassTest{intx;publicTest(Stringt){System.out.println(MTestH);}publicstaticvoidmain(String[]args){Testtest=null;System.out.println(test.x);}}1ஹTheprogramhasacompileerrorbecausetestisnotinitialized.2ஹTheprogramhasacompileerrorbecausexhasnotbeeninitialized.3ஹTheprogramhasacompileerrorbecauseyoucannotcreateanobjectfromtheclassthatdefinestheobject.4ஹTheprogramhasacompileerrorbecauseTestdoesnothaveadefaultconstructor.5ஹTheprogramhasaruntimeNullPointerExceptionbecausetestisnullwhileexecutingtest.x.'100⚪Analyzethefollowingcode:publicclassTest{publicstaticvoidmain(String[]args){doubleradius;finaldoublePl=3.15169;doublearea=radius*radius*PI;System.out.println(MAreais"+area);)}1ஹTheprogramhascompileerrorsbecausethevariableradiusisnotinitialized.2ஹTheprogramhasacompileerrorbecauseaconstantPIisdefinedinsideamethod.3ஹTheprogramhasnocompileerrorsbutwillgetaruntimeerrorbecauseradiusisnotinitialized.4ஹTheprogramcompilesandrunsfine.'101⚪Analyzethefollowingcode.publicclassTest{intx;publicTest(Stringt){System.out.println(,'TestM);)publicstaticvoidmain(String[]args){Testtest=newTest();
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶25

25System.out.println(test.x);)}1ஹTheprogramhasacompileerrorbecauseSystem.out.printlnmethodcannotbeinvokedfromtheconstructor.2ஹTheprogramhasacompileerrorbecausexhasnotbeeninitialized.3ஹTheprogramhasacompileerrorbecauseyoucannotcreateanobjectfromtheclassthatdefinestheobject.4ஹTheprogramhasacompileerrorbecauseTestdoesnothaveadefaultconstructor.'102⚪Thejava.util.DateclassisintroducedinSection7.4.Analyzethefollowingcodeandchoosethebestanswer:WhichofthefollowingcodeinAorB,orbothcreatesanobjectoftheDateclass:A:publicclassTest{publicTest(){newjava.util.Date();})B:publicclassTest{publicTest(){java.util.Datedate=newjava.util.Date();))1ஹA.2ஹB.3ஹNeither'103⚪Youshouldaddthestatickeywordintheplaceof?inLineinthefollowingcode:1publicclassTest{2privateintage;34public?intsquare(intn){5returnn*n;6)78public?intgetAge(){9)10)1ஹinline42ஹinline83ஹinbothline4andline8

26
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶264ஹnone'104⚪Analyzethefollowingcode,publicclassTest{publicstaticvoidmain(String[]args){intn=2;xMethod(n);System.out.println("nis"+n);)voidxMethod(intn){n++;)}1ஹThecodehasacompileerrorbecausexMethoddoesnotreturnavalue.2ஹThecodehasacompileerrorbecausexMethodisnotdeclaredstatic.3^Thecodeprintsnis1.4ஹThecodeprintsnis2.5ஹThecodeprintsnis3.'105^iWhatistheprintoutofthesecondprintinstatementinthemainmethod?publicclassFoo{inti;staticints;publicstaticvoidmain(String[]args){Foof1=newFoo();System.out.println("f1.iisM+f1.i+Mf1.sis"+f1.s);Foof2=newFoo();System.out.println("f2.iis”+f2.i+°f2.sis"+f2.s);Foof3=newFoo();System.out.println("f3.iis”+f3.i+''f3.sis"+f3.s);}publicFoo(){i++4s++;}}1ஹf2.iis1f2.sis12ஹf2.iis1f2.sis23ஹf2.iis2f2.sis24ஹf2.iis2f2.sis1'106⚪Whatistheprintoutofthethirdprintinstatementinthemainmethod?publicclassFoo{

27inti;staticints;
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶27publicstaticvoidmain(String[]args){Foof1=newFoo();System.out.println("f1Jis**+f1.i+Mf1.sis"+f1.s);Foof2=newFoo();System.out.println(Mf2.iis"+f2.i+*'f2.sis"+f2.s);Foof3=newFoo();System.out.println("f3.iis"+f3.i+Mf3.sis”+f3.s);)publicFoo(){i++4s++;}}1ஹf3.iis1f3.sis12ஹf3.iis1f3.sis23ஹf3.iis1f3.sis34ஹf3.iis3f3.sis15ஹf3.iis3f3.sis3'107⚪Analyzethefollowingcode:publicclassTest{publicstaticvoidmain(Stringargs[]){NCIassnc=newNCIass();nc.t=nc.t++;}}classNCIass{intt;privateNCIass(){))1ஹTheprogramhasacompilationerrorbecausetheNCIassclasshasaprivateconstructor.2ஹTheprogramdoesnotcompilebecausetheparameterlistofthemainmethodiswrong.3ஹTheprogramcompiles,buthasaruntimeerrorbecausethasnoinitialvalue.4ஹTheprogramcompilesandrunsfine.'108⚪Analyzethefollowingcode:publicclassTest{privateintt;

28publicstaticvoidmain(String[]args){intx;System.out.println(t);
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶28}}1ஹThevariabletisnotinitializedandthereforecauseserrors.2ஹThevariabletisprivateandthereforecannotbeaccessedinthemainmethod.3ஹtisnon-staticanditcannotbereferencedinastaticcontextinthemainmethod.4ஹThevariablexisnotinitializedandthereforecauseserrors.5ஹTheprogramcompilesandrunsfine.'109⚪Analyzethefollowingcodeandchoosethebestanswer:publicclassFoo{privateintx;publicstaticvoidmain(String[]args){Footoo=newFoo();System.out.println(foo.x);}}1ஹSincexisprivate,itcannotbeaccessedfromanobjecttoo.2ஹSincexisdefinedintheclassFoo,itcanbeaccessedbyanymethodinsidetheclasswithoutusinganobject.Youcanwritethecodetoaccessxwithoutcreatinganobjectsuchastoointhiscode.3ஹSincexisaninstancevariable,itcannotbedirectlyusedinsideamainmethod.However,itcanbeaccessedthroughanobjectsuchastoointhiscode.4ஹYoucannotcreateaself-referencedobject;thatis,tooiscreatedinsidetheclassFoo.'110⚪Wheninvokingamethodwithanobjectargument,ispassed.1ஹthecontentsoftheobject2ஹacopyoftheobject3^thereferenceoftheobject4ஹtheobjectiscopied,thenthereferenceofthecopiedobject'111⚪WhatisthevalueofmyCount.countdisplayed?publicclassTest{publicstaticvoidmain(String[]args){CountmyCount=newCount();inttimes=0;for(inti=0;i<100;i++)increment(myCount,times);

29System.out.println(“myCount.count=M+myCount.count);System.out.println("times="+times);}publicstaticvoidincrement(Countc,inttimes){
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶29c.count++;times++;)}classCount{intcount;Count(intc){count=c;}Count(){count=1;})1ஹ1012ஹ1003ஹ994ஹ98'112⚪Whatisthevalueoftimesdisplayed?publicclassTest{publicstaticvoidmain(String[]args){CountmyCount=newCount();inttimes=0;for(inti=0;i<100;i++)increment(myCount,times);System.out.println(•'myCount.count=M+myCount.count);System.out.println("times=*'+times);}publicstaticvoidincrement(Countc,inttimes){c.count++;times++;}}classCount{intcount;Count(intc){count=c;

30Count(){count=1;}}1ஹ1012ஹ100
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶303ஹ994ஹ985ஹ0'113⚪GiventhedeclarationCircledx=newCircle[10],whichofthefollowingstatementismostaccurate.1ஹxcontainsanarrayoftenintvalues.2ஹxcontainsanarrayoftenobjectsoftheCircletype.3ஹxcontainsareferencetoanarrayandeachelementinthearraycanholdareferencetoaCircleobject.4ஹxcontainsareferencetoanarrayandeachelementinthearraycanholdaCircleobject.'114⚪Assumejava.util.Date[]dates=newjava.util.Date[10],whichofthefollowingstatementsaretrue?1ஹdatesisnull.2ஹdates[0]isnull.3ஹdates=newjava.util.Date[5]isfine,whichassignsanewarraytodates.4ஹdates=newDate()isfine,whichcreatesanewDateobjectandassignstodates.'115⚪Whichofthefollowingstatementsaretrueaboutanimmutableobject?1ஹThecontentsofanimmutableobjectcannotbemodified.2ஹAllpropertiesofanimmutableobjectmustbeprivate.3ஹAllpropertiesofanimmutableobjectmustbeofprimitivetypes.4ஹAnobjecttypepropertyinanimmutableobjectmustalsobeimmutable.5ஹAnimmutableobjectcontainsnomutatormethods.'116⚪Whatistheprintoutforthefirststatementinthemainmethod?publicclassFoo{staticinti=0;staticintj=0;publicstaticvoidmain(String[]args){inti=2;intk=3;intj=3;System.out.println(Hi+jis"+i+j);

31System.out.println(Mkis"+k);System.outprintln("jis”+j);}}1ஹi+jis52ஹi+jis63ஹi+jis22
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶314ஹi+jis23'117⚪Whatistheprintoutforthesecondstatementinthemainmethod?publicclassFoo{staticinti=0;staticintj=0;publicstaticvoidmain(String[]args){inti=2;intk=3;(intj=3;System.out.println(Hi+jisM+i+j);)k=i+j;System.out.println(Mkis"+k);System.out.printingis"+j);)}1ஹkisO2ஹkis13ஹkis24ஹkis3'118⚪Whatistheprintoutforthethirdstatementinthemainmethod?publicclassFoo{staticinti=0;staticintj=0;publicstaticvoidmain(StringQargs){inti=2;intk=3;(intj=3;System.out.println(Mi+jis"+i+j);)k=i+j;

32System.out.println(Mkis"+k);System.out.println(Mjis"+j);}}1ஹjisO2ஹjis13ஹjis24ஹjis3'119⚪Analyzethefollowingcode:classCircle{privatedoubleradius;
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶32publicCircle(doubleradius){radius=radius;}}1ஹTheprogramhasacompilationerrorbecauseitdoesnothaveamainmethod.2ஹTheprogramwillcompile,butyoucannotcreateanobjectofCirclewithaspecifiedradius.Theobjectwillalwayshaveradius0.3ஹTheprogramhasacompilationerrorbecauseyoucannotassignradiustoradius.4ஹTheprogramdoesnotcompilebecauseCircledoesnothaveadefaultconstructor.'120⚪Analyzethefollowingcode:classTest{privatedoublei;publicTest(doublei){this.t();this.i=i;}publicTest(){System.out.println(MDefaultconstructor1');this(1);}publicvoidt(){System.out.println(HlnvokingtH);}}1ஹthis.t()maybereplacedbyt().2ஹthis.imaybereplacedbyi.3ஹthis(1)mustbecalledbeforeSystem.out.println("Defaultconstructor*1).4ஹthis(1)mustbereplacedbythis(1.0).

33'121⚪Object-orientedprogrammingallowsyoutoderivenewclassesfromexistingclasses.Thisiscalled.1ஹencapsulation2ஹinheritance3ஹabstraction4ஹgeneralization'122⚪SupposeyoucreateaclassCylindertobeasubclassofCircle.Analyzethefollowingcode:classCylinderextendsCircle{doublelength;Cylinder(doubleradius){Circle(radius);
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶33}}1ஹTheprogramcompilesfine,butyoucannotcreateaninstanceofCylinderbecausetheconstructordoesnotspecifythelengthofthecylinder.2ஹTheprogramhasacompileerrorbecauseyouattemptedtoinvoketheCircleclasssconstructorillegally.3ஹTheprogramcompilesfine,butithasaruntimeerrorbecauseofinvokingtheCircleclasssconstructorillegally.'123⚪Analyzethefollowingcode:importjava.util.StringTokenizer;publicclassAextendsStringTokenizer{)1ஹTheprogramhasacompilationerrorbecauseAdoesnothaveadefaultconstructor.2ஹTheprogramhasacompilationerrorbecausethedefaultconstructorofAinvokesthedefaultconstructorofStringTokenizer,butStringTokenizerdoesnothaveadefaultconstructor.3ஹTheprogramwouldcompilefineifyouaddthefollowingconstructorintoA:A(Strings){}4ஹTheprogramwouldcompilefineifyouaddthefollowingconstructorintoA:A(Strings){super(s);}'124⚪Analyzethefollowingcode:publicclassTestextendsA{publicstaticvoidmain(StringDargs){Testt=newTest();tprint();))classA{Strings;

34A(Strings){this.s=s;}publicvoidprint(){System.out.println(s);}}1ஹTheprogramdoesnotcompilebecauseTestdoesnothaveadefaultconstructorTest().2ஹTheprogramhasanimplicitdefaultconstructorTest(),butitcannotbecompiled,becauseitssuperclassdoesnothaveadefaultconstructor.TheprogramwouldcompileiftheconstructorintheclassAwereremoved.3ஹTheprogramwouldcompileifadefaultconstructorA(){}isaddedtoclassAexplicitly.
ᩈᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶344^Theprogramcompiles,butithasaruntimeerrorduetotheconflictonthemethodnameprint.'125⚪WhatistheoutputofrunningclassC?classA{publicA(){System.out.println(“ThedefaultconstructorofAisinvoked");}}classBextendsA{publicB(){System.out.println("ThedefaultconstructorofBisinvoked");))publicclassC{publicstaticvoidmain(StringDargs){Bb=newB();}}1ஹNothingdisplayed2ஹ"ThedefaultconstructorofBisinvoked',3ஹ“ThedefaultconstructorofAisinvoked,M'ThedefaultconstructorofBisinvoked**4ஹ“ThedefaultconstructorofBisinvoked,M'ThedefaultconstructorofAisinvoked**5ஹ“ThedefaultconstructorofAisinvoked11'126⚪Analyzethefollowingcode:

35publicclassTest{publicstaticvoidmain(String[]args){Bb=newB();b.m(5);System.out.println("iis"+b.i);}}classA{inti;publicvoidm(inti){this.i=i;))classBextendsA{publicvoidm(Strings){
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶35}}1ஹTheprogramhasacompilationerror,becausemisoverriddenwithadifferentsignatureinB.2ஹTheprogramhasacompilationerror,becauseb.m(5)cannotbeinvokedsincethemethodm(int)ishiddeninB.3ஹTheprogramhasaruntimeerroronb.i,becauseiisnotaccessiblefromb.4ஹThemethodmisnotoverriddeninB.BinheritsthemethodmfromAanddefinesanoverloadedmethodminB.'127⚪Analyzethefollowingcode:publicclassTest{publicstaticvoidmain(StringDargs){Objecta1=newA();Objecta2=newObject();System.out.println(a1);System.out,println(a2);}}classA{intx;publicStringtoString(){return"Asxisn+x;))1ஹTheprogramcannotbecompiled,becauseSystem.out.println(a1)iswronganditshouldbereplacedbySystem.out.println(a1.toString());

362ஹWhenexecutingSystem.out.println(a1),thetoString()methodintheObjectclassisinvoked.3^WhenexecutingSystem.out.println(a2),thetoString()methodintheObjectclassisinvoked.4ஹWhenexecutingSystem.out.println(a1),thetoString()methodintheAclassisinvoked.'128⚪Whatistheoutputofthefollowingcode:publicclassTest{publicstaticvoidmain(String[]args){Objecto1=newObject();Objecto2=newObject();System.out.print((o1==o2)+""+(o1.equals(o2)));)}1ஹfalsefalse2ஹtruetrue3^falsetrue
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶364ஹtruefalse'129⚪Whatistheoutputofthefollowingcode:publicclassTest{publicstaticvoidmain(String[]args){Strings1=newString(nJavaH);Strings2=newString("JavaH);System.out,print((s1==s2)+MH+(s1.equals(s2)));)}1ஹfalsefalse2ஹtruetrue3ஹfalsetrue4ஹtruefalse'130⚪Analyzethefollowingcode.//Program1:publicclassTest{publicstaticvoidmain(String[]args){Objecta1=newA();Objecta2=newA();System.out.println(a1.equals(a2));})classA{intx;publicbooleanequals(Objecta){

37returnthis.x==((A)a)x;}}//Program2:publicclassTest{publicstaticvoidmain(String[]args){Objecta1=newA();Objecta2=newA();System.out.println(a1.equals(a2));}}classA{intx;publicbooleanequals(Aa){returnthis.x==a.x;}}1ஹProgram1displaystrueandProgram2displaystrue2ஹProgram1displaysfalseandProgram2displaystrue
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶373ஹProgram1displaystrueandProgram2displaysfalse4ஹProgram1displaysfalseandProgram2displaysfalse'131⚪Analyzethefollowingcode.//Program1:publicclassTest{publicstaticvoidmain(String[]args){Objecta1=newA();Objecta2=newA();System.out.println(a1.equals(a2));)}classA{intx;publicbooleanequals(Aa){returnthis.x==a.x;}}//Program2:publicclassTest{publicstaticvoidmain(StringQargs){Aa1=newA();Aa2=newA();System.out.println(a1.equals(a2));

38}classA{intx;publicbooleanequals(Aa){returnthis.x==a.x;})1ஹProgram1displaystrueandProgram2displaystrue2ஹProgram1displaysfalseandProgram2displaystrue3ஹProgram1displaystrueandProgram2displaysfalse4ஹProgram1displaysfalseandProgram2displaysfalse'132⚪Analyzethefollowingcode.//Program1publicclassTest{publicstaticvoidmain(String[]args){Objecta1=newA();Objecta2=newA();System.out.println(((A)a1).equals((A)a2));)}
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶38classA{intx;publicbooleanequals(Aa){returnthis.x==a.x;}}//Program2publicclassTest{publicstaticvoidmain(StringQargs){Aa1=newA();Aa2=newA();System.out.println(a1.equals(a2));}}classA{intx;publicbooleanequals(Aa){returnthis.x==a.x;))1ஹProgram1displaystrueandProgram2displaystrue

392ஹProgram1displaysfalseandProgram2displaystrue3ஹProgram1displaystrueandProgram2displaysfalse4ஹProgram1displaysfalseandProgram2displaysfalse'133⚪Giventhefollowingcode,findthecompileerror?publicclassTest{publicstaticvoidmain(String[]args){m(newGraduateStudent());m(newStudent());m(newPerson());m(newObject());}publicstaticvoidm(Studentx){System.out.println(x.toStringO);}}classGraduatestudentextendsStudent{}classStudentextendsPerson{publicStringtoString(){return"Student0;}}classPersonextendsObject{
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶39publicStringtoString(){return"Person**;})1ஹm(newGraduateStudent())causesanerror2ஹm(newStudent())causesanerror3ஹm(newPerson())causesanerror4ஹm(newObject())causesanerror'134⚪Giventhefollowingclassesandtheirobjects:classC1{};classC2extendsC1{};classC3extendsC1{};C2c2=newC2();C3c3=newC3();Analyzethefollowingstatement:c2=(C2)((C1)c3);1ஹc3iscastintoc2successfully.2ஹYouwillgetaruntimeerrorbecauseyoucannotcastobjectsfromsiblingclasses.

403^YouwillgetaruntimeerrorbecausetheJavaruntimesystemcannotperformmultiplecastinginnestedform.4ஹThestatementiscorrect.'135⚪Giventhefollowingcode:classC1{}classC2extendsC1{}classC3extendsC2{}classC4extendsC1{}C1c1=newC1();C2c2=newC2();C3c3=newC3();C4c4=newC4();Whichofthefollowingexpressionsevaluatestofalse?1ஹc1instanceofC12ஹc2instanceofC13ஹc3instanceofC14ஹc4instanceofC2'136⚪YoucanassigntoavariableofObject[]type.1ஹnewchar[100]2ஹnewint[100]3ஹnewdouble[100]4ஹnewString[100]5ஹnewjava.util.Date[100]
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶40'137⚪SupposeArrayListxcontainstwostrings[Beijing,Singapore].Whichofthefollowingmethodswillcausethelisttobecome[Beijing,Chicago,Singapore]?1ஹx.add("Chicago")2ஹx.add(0,“Chicago”)3ஹx.add(1,^Chicago1')4ஹx.add(2,"Chicago")'138⚪SupposeArrayListxcontainstwostrings[Beijing,Singapore].Whichofthefollowingmethodwillcausethelisttobecome[Beijing]?1ஹx.removeC'Singapore")2ஹx.remove(O)3ஹx.remove(1)4ஹx.remove(2)/139⚪Analyzethefollowingcode:ArrayListlist=newArrayList();list.add("Beijing");list.addCTokyo1');list.addC'ShanghaiM);list.set(3,MHongKong**);

411ஹThelastlineinthecodecausesaruntimeerrorbecausethereisnoelementatindex3inthearraylist.2ஹThelastlineinthecodehasacompileerrorbecausethereisnoelementatindex3inthearraylist.3ஹIfyoureplacethelastlinebylist.add(3,nHongKong")thecodewillcompileandrunfine.4ஹIfyoureplacethelastlinebylist.add(4,nHongKong")thecodewillcompileandrunfine.'140⚪Whatmodifiershouldyouuseonthemembersofaclasssothattheyarenotaccessibletoanotherclassinadifferentpackage,butareaccessibletoanysubclassesinanypackage?1ஹpublic2ஹprivate3ஹprotected4ஹUsethedefaultmodifier.'141⚪Whichofthefollowingclassescannotbeextended?1ஹclassA{}2ஹclassA{privateA();}3^finalclassA{}4ஹclassA{protectedA();}'142⚪ThegetValue()methodisoverriddenintwoways.Whichoneiscorrect?I:publicclassTest{publicstaticvoidmain(String[]args){
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶41Aa=newA();System.out.println(a.getValue());})classB{publicStringgetValue(){return"Anyobject";}}classAextendsB{publicObjectgetValue(){return"Astring*';})II:publicclassTest{publicstaticvoidmain(String[]args){

42Aa=newA();System.out.println(a.getValue());}}classB{publicObjectgetValue(){return*'Anyobject";)}classAextendsB{publicStringgetValue(){returnMAstring*';)}1>I2ஹII3^BothIandII4ஹNeither'143:Whichofthefollowingclassdefinitionsdefinesalegalabstractclass?1ஹclassA{abstractvoidunfinished(){}}2ஹclassA{abstractvoidunfinished();}3ஹabstractclassA{abstractvoidunfinished();}4ஹpublicclassabstractA{abstractvoidunfinished();}'144⚪WhichofthefollowingdeclaresanabstractmethodinanabstractJavaclass?1ஹpublicabstractmethod();
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶422ஹpublicabstractvoidmethod();3ஹpublicvoidabstractMethod();4ஹpublicvoidmethod(){}5ஹpublicabstractvoidmethod(){}'145⚪Whichofthefollowingstatementsregardingabstractmethodsaretrue?1ஹAnabstractclasscanhaveinstancescreatedusingtheconstructoroftheabstractclass.2ஹAnabstractclasscanbeextended.3ஹAsubclassofanon-abstractsuperclasscanbeabstract.4ஹAsubclasscanoverrideaconcretemethodinasuperclasstodeclareitabstract.5ஹAnabstractclasscanbeusedasadatatype.'146⚪Whichofthefollowingstatementsregardingabstractmethodsaretrue?

431ஹAbstractclasseshaveconstructors.2ஹAclassthatcontainsabstractmethodsmustbeabstract.3^Itispossibletodeclareanabstractclassthatcontainsnoabstractmethods.4ஹAnabstractmethodcannotbecontainedinanonabstractclass.5ஹAdatafieldcanbedeclaredabstract.'147⚪WhatistheoutputofrunningclassTest?publicclassTest{publicstaticvoidmain(String[]args){newCircle9();})publicabstractclassGeometricObject{protectedGeometricObject(){System.out.print("A");}protectedGeometricObject(Stringcolor,booleanfilled){System.out.print("B");})publicclassCircledextendsGeometricObject{/**Defaultconstructor*/publicCircle9(){this(1.0);System.out.print(,,CM);)/**Constructcirclewithaspecifiedradius*/publicCircle9(doubleradius){this(radius,"white",false);
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶43System.out.print("DM);)/**Constructacirclewithspecifiedradius,filled,andcolor*/publicCircle9(doubleradius,Stringcolor,booleanfilled){super(color,filled);System.out.print(''E");}}1ஹABCD2ஹBACD3ஹCBAE4ஹAEDC5ஹBEDC

44'148⚪Thejava.util.Calendarandjava.util.GregorianCalendarclassesareintroducedinChapter11.Analyzethefollowingcode.1.importjava.util.*;2.publicclassTest{3.publicstaticvoidmain(String[]args){4.Calendar[]calendars=newCalendar[10];5.calendars[O]=newCalendar();6.calendars[1]=newGregorianCalendar();7.)8.}1ஹTheprogramhasacompileerroronLine4becausejava.util.Calendarisanabstractclass.2ஹTheprogramhasacompileerroronLine5becausejava.util.Calendarisanabstractclass.3ஹTheprogramhasacompileerroronLine6becauseCalendar[1]isnotofaGregorianCalendartype.4ஹTheprogramhasnocompileerrors.'149⚪ShowtheoutputofrunningtheclassTestinthefollowingcodelines:interfaceA{}classC{}classBextendsDimplementsA{}publicclassTestextendsThread{publicstaticvoidmain(String[]args){Bb=newB();if(binstanceofA)System.out.println(HbisaninstanceofA");if(binstanceofC)
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶44System.out.println("bisaninstanceofS');}}classDextendsC{}1ஹNothing.2ஹbisaninstanceofA.3ஹbisaninstanceofC.4ஹbisaninstanceofAfollowedbybisaninstanceofC.'150⚪Thejava.Iang.ComparableinterfaceisintroducedinChapter11.Analyzethefollowingcode:

45publicclassTesti{publicObjectmax(Objecto1,Objecto2){if((Comparable)o1.compareTo(o2)>=0){returno1;}else(returno2;)}}1ஹTheprogramhasacompileerrorbecauseTestidoesnothaveamainmethod.2ஹTheprogramhasacompileerrorbecauseo1isanObjectinstanceanditdoesnothavethecompareTomethod.3ஹTheprogramhasacompileerrorbecauseyoucannotcastanObjectinstanceo1intoComparable.4ஹTheprogramwouldcompileif((Comparable)o1.compareTo(o2)>=0)isreplacedby(((Comparable)o1).compareTo(o2)>=0).'151⚪Analyzethefollowingcode.1.publicclassTest{2.publicstaticvoidmain(String[]args){3.Fruit[]fruits={newFruit(2),newFruit(3),newFruitপ};4.java.util.Arrays.sort(fruits);5.}6.}classFruit{privatedoubleweight;publicFruit(doubleweight){this.weight=weight;)}1ஹTheprogramhasacompileerrorbecausetheFruitclassdoesnothaveadefaultconstructor.
ᧇᩭὶ2007ᢈᵨ஺ᑁᧇ஺!"ᵨ#ᐸ%ᵨ⌶452ஹTheprogramhasaruntimeerroronLine3becausetheFruitclassdoesnothaveadefaultconstructor.3ஹTheprogramhasacompileerroronLine4becausetheFruitclassdoesnotimplementthejava.Iang.ComparableinterfaceandtheFruitobjectsarenotcomparable.4ஹTheprogramhasaruntimeerroronLine4becausetheFruitclassdoesnotimplementthejava.Iang.ComparableinterfaceandtheFruitobjectsarenotcomparable.'152⚪InJDK1.5,analyzethefollowingcode.

46Line1:IntegerQintArray={1,2,3};Line2:inti=intArray[O]+intArray[1];Line3:intj=i+intArray[2];Line4:doubled=intArray[O];1ஹItisOKtoassign1,2,3toanarrayofIntegerobjectsinJDK1.5.2ஹItisOKtoautomaticallyconvertanIntegerobjecttoanintvalueinLine2.3ஹItisOKtomixanintvaluewithanIntegerobjectinanexpressioninLine3.4ஹLine4isOK.AnintvaluefromintArray[0]objectisassignedtoadoublevariabled.'153⚪Whichstatementsaremostaccurateregardingthefollowingclasses?classA{privateinti;protectedintj;}classBextendsA{privateintk;protectedintm;}1ஹAnobjectofBcontainsdatafieldsi,j,k,m.2ஹAnobjectofBcontainsdatafieldsj,k,m.3ஹAnobjectofBcontainsdatafieldsj,m.4.AnobjectofBcontainsdatafieldsk,m.