java认证之SCJP考试试题及答案讲解文档格式.docx
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java认证之SCJP考试试题及答案讲解文档格式.docx
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12.//insertcodehere
14.}
Whichtwocodefragments,insertedindependentlyatline12,willallow
theclasstocompile?
(Choosetwo.)
A.foreach(x)System.out.println(z);
B.for(intz:
x)System.out.println(z);
C.while(x.hasNext())System.out.println(x.next());
D.for(inti=0;
i<
x.length;
i++)System.out.println(x[i]);
BD
Question3
11.publicclassTest{
12.publicstaticvoidmain(String[]args){
13.intx=5;
14.booleanb1=true;
15.booleanb2=false;
16.
17.if((x==4)&
&
!
b2)
18.System.out.print("
l"
);
19.System.out.print("
2"
20.if((b2=true)&
b1)
21.System.out.print("
3"
22.}
23.}
Whatistheresult?
A.2
B.3
C.12
D.23
E.123
F.Compilationfails.
G.Auexceptionalisthrownatruntime.
D
Question4
11.String[]elements={"
for"
"
tea"
too"
};
12.Stringfirst=(elements.length>
0)?
elements[0]:
null;
A.Compilationfails.
B.Anexceptionisthrownatruntime.
C.Thevariablefirstissettonull.
D.Thevariablefirstissettoelements[0].
Question5
10.interfaceFoo{}
11.classAlphaimplementsFoo{}
12.classBetaextendsAlpha{}
13.classDeltaextendsBeta{
14.publicstaticvoidmain(String[]args){
15.Betax=newBeta();
16.//insertcodehere
17.}
18.}
Whichcode,insertedatline16,willcausea
java.lang.ClassCastException?
A.Alphaa=x;
隐式向上造型
B.Foof=(Delta)x;
beta不能转换为delta
C.Foof=(Alpha)x;
D.Betab=(Beta)(Alpha)x;
B
Question6
11.classCup{}
12.classPoisonCupextendsCup{}
21.publicvoidtakeCup(Cupc){
22.if(cinstanceofPoisonCup){
23.System.out.println("
Inconceivable!
"
24.}elseif(cinstanceofCup){
25.System.out.println("
Dizzyingintellect!
26.}else{
27.System.exit(0);
28.}
29.}
Andtheexecutionofthestatements:
Cupcup=newPoisonCup();
takeCup(cup);
Whatistheoutput?
A.Inconceivable!
B.Dizzyingintellect!
C.Thecoderunswithnooutput.
D.Anexceptionisthrownatruntime.
E.Compilationfailsbecauseofanerrorinline22.
A
Question7
11.publicstaticvoidtest(Stringstr){
12.if(str==null|str.length()==0){//空指针异常|非短路str.length()==0也会执行所以空指针异常
13.System.out.println("
Stringisempty"
14.}else{
15.System.out.println("
Stringisnotempty"
16.}
17.}
Andtheinvocation:
31.test(null);
A.Anexceptionisthrownatruntime.
B."
isprintedtooutput.
C.Compilationfailsbecauseofauerrorinline12.
D."
Question8
10.publicclassMyClass{
11.
12.publicIntegerstartingI;
13.publicvoidmethodA(){
14.Integeri=newInteger(25);
15.startingI=i;
16.methodB(i);
18.privatevoidmethodB(Integeri2){
19.i2=i2.intValue();
20.
21.}
IfmethodAisinvoked,whichtwoaretrueatline20?
A.i2==startingIreturnstrue.
B.i2==startingIreturnsfalse.
C.i2.equals(startingI)returnstrue.
D.i2.equals(startingI)returnsfalse.
BC
Question9
WhichManclassproperlyrepresentstherelationship"
Manhasabest
friendwhoisaDog"
?
A.classManextendsDog{}
B.classManimplementsDog{}
C.classMan{privateBestFrienddog;
}
D.classMan{privateDogbestFriend;
E.classMan{privateDog<
bestFriend>
F.classMan{privateBestFriend<
dog>
}//无变量
Question10
11.publicclassItemTest{
12.privatefinalintid;
13.publicItemTest(intid){this.id=id;
14.publicvoidupdateId(intnewId){id=newId;
15.
16.publicstaticvoidmain(String[]args){
17.ItemTestfa=newItemTest(42);
18.fa.updateId(69);
19.System.out.println(fa.id);
20.}
C.TheattributeidintheItemobjectremainsunchanged.
D.TheattributeidintheItemobjectismodifiedtothenewvalue.
E.AnewItemobjectiscreatedwiththepreferredvalueintheid
attribute.
Question11
15.publicclassYippee{
16.publicstaticvoidmain(String[]args){
17.for(intx=1;
x<
args.length;
x++){
18.System.out.print(args[x]+"
"
19.}
andtwoseparatecommandlineinvocations:
javaYippee
javaYippee1234
A.Nooutputisproduced.
123
B.Nooutputisproduced.
234
C.Nooutputisproduce
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