Java程序员认证考试244题.docx
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Java程序员认证考试244题
第1題
Given:
35.String#name="JaneDoe";
36.int$age=24;
37.Double_height=123.5;
38.double~temp=37.5;
Whichtwostatementsaretrue?
（Choosetwo.）
A.Line35willnotcompile.
B.Line36willnotcompile.
C.Line37willnotcompile.
D.Line38willnotcompile.
第2題
Given:
1.publicclassTestString1{
2.publicstaticvoidmain（String[]args）{
3.Stringstr="420";
4.str+=42;
5.System.out.print（str）;
6.}
7.}
Whatistheoutput?
A.42
B.420
C.462
D.42042
E.Compilationfails.
F.Anexceptionisthrownatruntime.
第3題
Given:
1.publicclassTest{
2.publicstaticvoidmain（String[]args）{
3.intx=5;
4.booleanb1=true;
5.booleanb2=false;
6.
7.if（（x==4）&&!
b2）
8.System.out.print（"1"）;
9.System.out.print（"2"）;
10.if（（b2=true）&&b1）
11.System.out.print（"3"）;
12.}
13.}
Whatistheresult?
A.2
B.3
C.12
D.23
E.123
F.Compilationfails.
G.Anexceptionisthrownatruntime.
第4題
Given:
22.publicvoidgo（）{
23.Stringo="";
24.z:
25.for（intx=0;x<3;x++）{
26.for（inty=0;y<2;y++）{
27.if（x==1）break;
28.if（x==2&&y==1）breakz;
29.o=o+x+y;
30.}
31.}
32.System.out.println（o）;
33.}
Whatistheresultwhenthego（）methodisinvoked?
A.00
B.0001
C.000120
D.00012021
E.Compilationfails.
F.Anexceptionisthrownatruntime.
第5題
Given:
10.intx=0;
11.inty=10;
12.do{
13.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
第6題
Given:
1.publicclassBreaker{
2.staticStringo="";
3.publicstaticvoidmain（String[]args）{
4.z:
5.o=o+2;
6.for（intx=3;x<8;x++）{
7.if（x==4）break;
8.if（x==6）breakz;
9.o=o+x;
10.}
11.System.out.println（o）;
12.}
13.}
Whatistheresult?
A.23
B.234
C.235
D.2345
E.2357
F.23457
G.Compilationfails.
第7題
Given:
1.publicclassBreaker2{
2.staticStringo="";
3.publicstaticvoidmain（String[]args）{
4.z:
5.for（intx=2;x<7;x++）{
6.if（x==3）continue;
7.if（x==5）breakz;
8.o=o+x;
9.}
10.System.out.println（o）;
11.}
12.}
Whatistheresult?
A.2
B.24
C.234
D.246
E.2346
F.Compilationfails.
第8題
Given:
1.publicclassSpock{
2.publicstaticvoidmain（String[]args）{
3.Longtail=2000L;
4.Longdistance=1999L;
5.Longstory=1000L;
6.if（（tail>distance）^（（story*2）==tail））
7.System.out.print（"1"）;
8.if（（distance+1!
=tail）^（（story*2）==distance））
9.System.out.print（"2"）;
10.}
11.}
Whatistheresult?
A.1
B.2
C.12
D.Compilationfails.
E.Nooutputisproduced.
F.Anexceptionisthrownatruntime.
第9題
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].
第10題
Given:
1.importjava.util.*;
2.publicclassQuest{
3.publicstaticvoidmain（String[]args）{
4.String[]colors=
5.{"blue","red","green","yellow","orange"};
6.Arrays.sort（colors）;
7.ints2=Arrays.binarySearch（colors,"orange"）;
8.ints3=Arrays.binarySearch（colors,"violet"）;
9.System.out.print（s2+""+s3）;
10.}
11.}
Whatistheresult?
A.2-1
B.2-4
C.2-5
D.3-1
E.3-4
F.3-5
G.Compilationfails.
H.Anexceptionisthrownatruntime.
第11題
Given:
1.classAlligator{
2.publicstaticvoidmain（String[]args）{
3.int[]x[]={{1,2},{3,4,5},{6,7,8,9}};
4.int[][]y=x;
5.System.out.print（y[2][1]）;
6.}
7.}
Whatistheresult?
A.2
B.3
C.4
D.6
E.7
F.Compilationfails.
第12題
DragandDrop（拖曳題）
AddmethodstotheBetaclasstomakeitcompilecorrectly.
classAlpha{
publicvoidbar（int...x）{}
publicvoidbar（intx）{}
}
publicclassBetaextendsAlpha{
Placehere
Placehere
Placehere
}
第13題
Given:
1.publicclassBarn{
2.publicstaticvoidmain（String[]args）{
privatevoidbar（intx）{}
publicvoidbar（intx）{}
publicintbar（Stringx）{return1;}
publicAlphabar（intx）{}
publicvoidbar（intx,inty）{}
publicintbar（intx）{returnx;}
Methods
3.newBarn.go（"hi",1）;
4.newBarn.go（"hi","world",2）;
5.}
6.publicvoidgo（String...y,intx）{
7.System.out.print（y[y.length-1]+""）;
8.}
9.}
Whatistheresult?
A.hihi
B.hiworld
C.worldworld
D.Compilationfails.
E.Anexceptionisthrownatruntime.
第14題
Given:
11.classPerson{
12.Stringname="Noname";
13.publicPerson（Stringnm）{name=nm;}
14.}
15.
16.classEmployeeextendsPerson{
17.StringempID="0000";
18.publicEmployee（Stringid）{empID=id;}
19.}
20.
21.classEmployeeTest{
22.publicstaticvoidmain（String[]args）{
23.Employeee=newEmployee（"4321"）;
24.System.out.println（e.empID）;
25.}
26.}
Whatistheresult?
A.4321
B.0000
C.Anexceptionisthrownatruntime.
D.Compilationfailsbecauseofanerrorinline18.
第15題
Given:
11.classMud{
12.//insertcodehere
13.System.out.println（"hi"）;
14.}
15.}
Andthefollowingfivefragments:
publicstaticvoidmain（String...a）{
publicstaticvoidmain（String.*a）{
publicstaticvoidmain（String...a）{
publicstaticvoidmain（String[]...a）{
publicstaticvoidmain（String...[]a）{
Howmanyofthecodefragments,insertedindependentlyatline12,compile?
A.0
B.1
C.2
D.3
E.4
F.5
第16題
Given:
5.classAtom{
6.Atom（）{System.out.print（"atom"）;}
7.}
8.classRockextendsAtom{
9.Rock（Stringtype）{System.out.print（type）;}
10.}
11.publicclassMountainextendsRock{
12.Mountain（）{
13.super（"granite"）;
14.newRock（"granite"）;
15.}
16.publicstaticvoidmain（String[]a）{newMountain（）;}
17.}
Whatistheresult?
A.Compilationfails.
B.atomgranite
C.granitegranite
D.atomgranitegranite
E.Anexceptionisthrownatruntime.
F.atomgraniteatomgranite
第17題
Given:
1.publicclassBlip{
2.protectedintblipvert（intx）{return0;}
3.}
4.classVertextendsBlip{
5.//insertcodehere
6.}
Whichfivemethods,insertedindependentlyatline5,willcompile?
（Choosefive.）
A.publicintblipvert（intx）{return0;}
B.privateintblipvert（intx）{return0;}
C.privateintblipvert（longx）{return0;}
D.protectedlongblipvert（intx）{return0;}
E.protectedintblipvert（longx）{return0;}
F.protectedlongblipvert（longx）{return0;}
G.protectedlongblipvert（intx,inty）{return0;}
第18題
Given:
1.classSuper{
2.privateinta;
3.protectedSuper（inta）{this.a=a;}
4.}
...
11.classSubextendsSuper{
12.publicSub（inta）{super（a）;}
13.publicSub（）{this.a=5;}
14.}
Whichtwo,independently,willallowSubtocompile?
（Choosetwo.）
A.Changeline2to:
publicinta;
B.Changeline2to:
protectedinta;
C.Changeline13to:
publicSub（）{this（5）;}
D.Changeline13to:
publicSub（）{super（5）;}
E.Changeline13to:
publicSub（）{super（a）;}
第19題
WhichManclassproperlyrepresentstherelationship"ManhasabestfriendwhoisaDog"?
A.classManextendsDog{}
B.classManimplementsDog{}
C.classMan{privateBestFrienddog;}
D.classMan{privateDogbestFriend;}
E.classMan{privateDog;}
F.classMan{privateBestFriend;}
第20題
AteamofprogrammersisreviewingaproposedAPIforanewutilityclass.Aftersomediscussion,they
realizethattheycanreducethenumberofmethodsintheAPIwithoutlosinganyfunctionality.Ifthey
implementthenewdesign,whichtwoOOprincipleswilltheybepromoting?
A.Loosercoupling
B.Tightercoupling
C.Lowercohesion
D.Highercohesion
E.Weakerencapsulation
F.Strongerencapsulation
第21題
Given:
1.classBatman{
2.intsquares=81;
3.publicstaticvoidmain（String[]args）{
4.newBatman（）.go（）;
5.}
6.voidgo（）{
7.incr（++squares）;
8.System.out.println（squares）;
9.}
10.voidincr（intsquares）{squares+=10;}
11.}
Whatistheresult?
A.81
B.82
C.91
D.92
E.Compilationfails.
F.Anexceptionisthrownatruntime.
第22題
Given:
1.classPass{
2.publicstaticvoidmain（String[]args）{
3.intx=5;
4.Passp=newPass（）;
5.p.doStuff（x）;
6.System.out.print（"mainx="+x）;
7.}
8.voiddoStuff（intx）{
9.System.out.println（"doStuffx="+x++）;
10.}
11.}
Whatistheresult?
A.Compilationfails.
B.Anexceptionisthrownatruntime.
C.doStuffx=6mainx=6
D.doStuffx=5mainx=5
E.doStuffx=5mainx=6
F.doStuffx=6mainx=5
第23題
Acompanyhasabusinessapplicationthatprovidesitsuserswithmanydifferentreports:
receivablesreports,payablesreports,revenueprojects,andsoon.Thecompanyhasjustpurchasedsomenew,state-of-the-art,wirelessprinters,andaprogrammerhasbeenassignedthetaskofenhancingallofthereportstousenotonlythecompany'soldprinters,butthenewwirelessprintersaswell.Whentheprogrammerstartslookingintotheapplication,theprogrammerdiscoversthatbecauseofthedesignoftheapplication,itisnecessarytomakechangestoeachreporttosupportthenewprinters.
Whichtwodesignconceptsmostlikelyexplainthesituation?
（Choosetwo.）
A.Inheritance
B.Lowcohesion
C.Tightcoupling
D.Highcohesion
E.Loosecoupling
F.Objectimmutablility
第24題
AcompanythatmakesComputerAssistedDesign（CAD）softwarehas,withinitsapplicationsomeutilityclassesthatareusedtoperform3Drenderingtasks.Thecompany'schiefscientisthasjustimprovedtheperformanceofoneoftheutilityclasses'keyrenderingalgorithms,
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