javasun试题3文档格式.docx
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javasun试题3文档格式.docx
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}isaddedtothePlantclass.
(D)
子类默认调用父类无参构造函数,而Plant没有无参构造函数,因此须显示调用有参构造函数
面向对象
QUESTION123
Whichtwocodefragments,insertedindependentlyatline12,willallowtheclasstocompile?
(Choosetwo.)
A.foreach(x)System.out.print1n(z);
B.for(intz:
x)System.out.print1n(z);
C.while(x.hashNext())System.out.print1n(x.next())
D.for(inti=0;
i<
x.length;
i++)System.out.println(x[i]);
(B,D)
可变参数方法编译后变成数组参数方法,然后利用循环结构取出数组的值
流程控制和可变长度参数
QUESTION124
Exhibit:
Whichstatementistrueabouttheclassesandinterfacesintheexhibit?
A.Compilationwillsucceedforallclassesandinterfaces.
B.CompilationofclassCwillfailbecauseofanerrorinline2.
C.CompilationofclassCwillfailbecauseofanerrorinline6.
D.CompilationofclassAImplwillfailbecauseofanerrorinline2.
(C)
面向对象—复写
QUESTION125
Placethelinesinthecorrectordertocompletetheenum。
enumElement{
()
EARTH,WIND,
FIRE{
publicStringinfo(){return“Hot”;
}
};
publicStringinfo(){return“element”;
列举的内容之后要加上“;
”
面向对象—enum
QUESTION126
PlacethecodeelementsinordersothattheresultingJavasourcefilewillcompile
correctly,resultinginaclasscalledcom.sun.cert.AddressBook.
packagecom.sum.cert;
importjava.util.*;
publicclassAddressBook{
ArrayListentries;
面向对象—语法基础
QUESTION127
Whichtwoclassescorrectlyimplementboththejava.lang.Runnableandthe
java.lang.Clonableinterfaces?
A.publicclassSessionimplementsRunnable,Clonable{
publicvoidrun();
publicObjectclone();
}
B.publicclassSessionextendsRunnable,Clonable{
publicvoidrun(){/*dosomething*/}
publicObjectclone(){/*makeacopy*/}
C.publicclassSessionimplementsRunnable,Clonable{
D.publicabstractclassSessionimplementsRunnable,Clonable{
E.publicclassSessionimplementsRunnable,implementsClonable{
(C,D)
A错误Session是具体类,方法必须实现
B实现interface用implements
C正确
D正确
E错误implements只能出现一次
多线程
QUESTION128
A.420istheoutput
B.Anexceptionisthrownatruntime.
C.Allconstructorsmustbedeclaredpublic.
D.ConstructorsCANNOTusetheprivatemodifier.
E.ConstructorsCANNOTusetheprotectedmodifier.
(A)
QUESTION129
Whatistheresult?
A.foofoofoofoofoo
B.foobarfoobarbar
C.foobarfoofoofoo
D.foobarfoobarfoo
E.barbarbarbarbar
F.foofoofoobarbar
G.foofoofoobarfoo
面向对象—属性的重载和遮蔽,该题中子类遮蔽了父类的属性
QUESTION130
Whichtwostatementsaretrueabouthas-aandis-arelationships?
A.Inheritancerepresentsanis-arelationship.
B.Inheritancerepresentsanhas-arelationship.
C.Interfacesmustbeusewhencreatingahas-arelationship.
D.Instancevariablescanbeusedwhencreatingahas-arelationship.
(A,D)
QUESTION131--------
Whichstatementistrueabouttheclassofanobjectthatcanreferencethevariablebase?
A.Itcanbeanyclass.
B.Noclasshasaccesstobase.
C.Theclassmustbelongtothegeometrypackage.
D.TheclassmustbeasubclassoftheclassHypotenuse.
QUESTION132
Placethenames"
A"
and"
B"
inthefollowingoutput.
面向对象classBhasnameA
QUESTION133
A.Compilationfailsbecauseofanerrorinline3.
B.Compilationfailsbecauseofanerrorinline7.
C.Compilationfailsbecauseofanerrorinline9.
D.IfyoudefineDe=newE(),thene.bMethod()invokestheversionofbMethod()
definedinline5.
E.IfyoudefineDe=(D)(newE()),thene.bMethod()invokestheversionofbMethod()
F.IfyoudefineDe=(D)(newE()),thene.bMethod()invokestheversionofbMethod()
definedinline9.
(F)E类的对象调用b.Method(),因为E类体里有这个方法就遮蔽了父类的方法
QUESTION134
Whichtwostatementsaretrue?
A.Anencapsulation,publicclasspromotesre-use.
B.Classesthatsharethesameinterfacearealwaystightlyencapsulated.
C.Anencapsulatedclassallowssubclassestooverloadmethods,butdoesNOTallow
overridingmethods.
D.Anencapsulatedclassallowsprogrammertochangeanimplementationwithout
affectingoutsidecode.
(A,D)
QUESTION135-----BT
PlacetheRelationsontheircorrespondingImplementationStructures.
Note:
NotallImplementationStructreswillbeused.
QUESTION136
And:
A.Hello
B.HelloWorld
C.Compilationfails.
D.HelloWorld5
E.Thecoderunswithnooutput.
F.Anexceptionisthrownatruntime.
19行应改为this(),应该放在第一行;
QUESTION137--
Whichtwo,independently,willallowSubtocompile?
A.Changeline2to:
publicinta;
B.Changeline2to:
protectedinta;
C.Changeline13to:
publicSub(){this(5);
D.Changeline13to:
publicSub(){super(5);
E.Changeline13to:
publicSub(){super(a);
QUESTION138--
Whatistheresultwhentheprogrammerattemptstocompilethecodeandrunitwiththecommand:
javaConverter12?
A.Itistruethatj==i.
B.Itisfalsethatj==i.
C.Anexceptionisthrownatruntime.
D.Compilationfailsbecauseofanerrorinline13.
语言基础
QUESTION139
Whatistheoutput?
A.42
B.420
C.462
D.42042
E.Compilationfails
QUESTION140--BT
AssumingthattheserializeBanana2()andthedeserializeBanana2()methodswill
correctlyuseJavaserializationandgiven:
A.Compilationfails
B.1restored42
C.12restored42
D.121restored42
E.1212restored42
F.Anexceptionisthrownatruntime
因为父类Food未实现serializable接口,反序列化时将调用Food的构造函数.见工程执行结果
IO操作—序列化机制
QUESTION141
A.abc
B.123
C.a1b2c3
D.a1b2c3
F.Thecoderunswithnooutput.
G.Anexceptionisthrownatruntime.
实用API
QUESTION142
B.Afterline15,thevalueofageis5.
C.Afterline15,thevalueofageis3.
D.Anexceptionisthrownatruntime.
抛出java.util.InputMismatchException异常
正确读取方法:
scaner.next();
scaner.nextInt();
scaner.nextBoolean();
实用API—Scanner简易I/O工具
QUESTION143
GivenavalidDateFormatobjectnameddf,and
Whatupdatesd'
svaluewiththedaterepresentedbyds?
A.A
B.B
C.C
D.D
DateFormat类的parse(Strings)会抛ParseException异常.
实用API—DataFormat
QUESTION144
PlacetheFragmentsintotheprogram,sothattheprogramwillgetlinesfromatextfile,displaythem,andthenclosealltheresources.
IO操作
QUESTION145
WhichchangescanyoumaketoTargetwithoutaffectingClient?
A.Line4ofclassTargetcanbechangedtoreturni++;
B.Line2ofclassTargetcanbechangedtoprivateinti=1;
C.Line3ofclassTargetcanbechangedtoprivateintaddOne(){
D.Line2ofclassTargetcanbechangedtoprivateIntegeri=0;
A:
return++i;
和returni++;
不一样.
QUESTION146
A.CompilationwillsucceedifAextendsB.
B.CompilationwillsucceedifBextendsA.
C.Compilationwillalwaysfailbecauseofanerrorinline7.
D.Compilationwillalwaysfailbecauseofanerrorinline8.
面向对象—重写
QUESTION147
A.Compilationfails.
B.CannotaddToppings
C.Thecoderunswithnooutput.
D.ANullPointerExceptionisthrowninLine4.
final方法不能重写
QUESTION148
Insertsixmodifiersintothecodesuchthatitmeetsalloftheserequirements:
2,4,8,9行符合条件一;
3行符合条件二;
5行符合条件三.
语言基础—存取权限
QUESTION149
A.Thecoderunswithnooutput.
C.Compilationfailsbecauseofanerrorinline20.
D.Compilationfailsbecauseofanerrorinline21.
E.Compilationfailsbecauseofanerrorinline23.
F.Compilationfailsbecauseofanerrorinline25.
(F)
a对象没有y()方法
QUESTION150
Aprogrammerneedstocreatealoggingmethodthatcanacceptanarbitrary
numberofarguments.Forexample,itmaybecalledintheseways:
Whichd
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