单项选择题

A.classAlpha{voidm1(){}}2.classBetaextendsAlpha{voidm2(){}}3.classGammaextendsBeta{}4.5.classGreekTest{6.publicstaticvoidmain(String[]args){7.aAlpha[]a={newAlpha(),newBeta(),newGamma()};8.for(Alphaa2:a){9.a2.m1();10.if(a2instanceofBeta||a2instanceofGamma)11.//insertcodehere12.}13.}14.}哪一行代码插入到第11行,将编译但是会在运行时产生异常?()
A.a2.m2();
B.((Beta)a2).m2();
C.((Alpha)a2).m2();
D.((Gamma)a2).m2();
相关考题

未知题型 常见的设备维护分析方法有哪些?()

单项选择题 程序:classMyDate{privateintyear;privateintmonth;privateintday;publicMyDate(intyear,intmonth,intday){this.year=year;this.month=month;this.day=day;}//OverrideMethod}为了让newMyDate(1980,11,9)==(判断是否相等)newMyDate(1980,11,9)返回true,必须在OverrideMethod处覆盖哪个方法?()A.hashCodeB.equalsC.toStringD.notify

未知题型 基站出现“OpticalInterfaceLink_OpticalInterfaceLinkFailure”告警可能是下面哪些原因造成地()

单项选择题 classTestMain{staticintx=2;static{x=4;}staticpublicvoidmain(String[]args){inty=x+1;System.out.println(y);}}和命令行:javaTestMain结果为:()

未知题型 以下操作可以再OSS中实现的是()

单项选择题 下述代码执行后,有几个引用变量和几个对象?()对象声明Studentstu(对象)=newStudent(Mike”);对象定义(开辟空间)Studentstua;(声明变量)Stua=stu;

未知题型 WCDMA网络中,小区总干扰为()

单项选择题 classParserextendsUtils{publicstaticvoidmain(String[]args){System.out.print(newParser().getInt("42"));}intgetInt(Stringarg){returnInteger.parseInt(arg);}}classUtils{intgetInt(Stringarg)throwsException{return42;}}结果为:()A.42B.编译失败C.无输出结果D.运行时异常被抛出

单项选择题 t是一个合法的Thread对象的引用,并且t的合法run()方法如下:publicvoidrun(){System.out.print("go");}及:t.start();t.start();t.run();哪一个是结果?()

单项选择题 以下哪个类与SwingGUI菜单类无关?()

单项选择题 classBird{staticvoidtalk(){System.out.print("chirp");}}classParrotextendsBird{staticvoidtalk(){System.out.print("hello");}publicstaticvoidmain(String[]args){Bird[]birds={newBird(),newParrot()};for(Birdb:birds)b.talk();}}结果为:()A.chirpchirpB.chirphelloC.hellohelloD.编译失败

单项选择题 现有:classCat{Cat(intc){System.out.print("cat"+c+"");}}classSubCatextendsCat{SubCat(intc){super(5);System.out.print("cable");}SubCat(){this(4);}publicstaticvoidmain(String[]args){SubCats=newSubCat();}}结果为:()A.cat5B.cableC.cablecat5D.cat5cable

单项选择题 现有:classThreadExceptimplementsRunnable{publicvoidrun(){thrownewRuntimeException("exception");}publicstaticvoidmain(String[]args){newThread(newThreadExcept()).start();try{intx=Integer.parseInt(args[0]);Thread.sleep(x);System.out.print("main");}catch(Exceptione){}}}和命令行:javaThreadExcept1000哪一个是结果?()A.mainB.编译失败C.代码运行,但没有输出D.mainjava.lang.RuntimeException:exception

单项选择题 1.interfaceAnimal{2.voideat();3.}4.5.//insertcodehere6.7.publicclassHouseCatimplementsFeline{8.publicvoideat(){}9.}和以下三个接口声明:interfaceFelineextendsAnimal{}interfaceFelineextendsAnimal{voideat();}interfaceFelineextendsAnimal{voideat(){}}分别插入到第5行,有多少行可以编译?()A.0B.1C.2D.3

单项选择题 publicclassEmployee{privateStringname;publicEmployee(Stringname){this.name=name;}publicvoiddisplay(){System.out.print(name);}}publicclassManagerextendsEmployee{privateStringdepartment;publicManager(Stringname,Stringdepartment){super(name);this.department=department;}publicvoiddisplay(){System.out.println(super.display()+”,”+department);}}执行语句newManager(smith”,”SALES”)后程序的输出是哪项?()A.smith,SALESB.null,SALESC.smith,nullD.null,null

单项选择题 publicclassEmployee{privateStringname;publicEmployee(Stringname){this.name=name;}publicStringgetName(){returnname;}}publicclassManagerextendsEmployee{publicManager(Stringname){System.out.println(getName());}}执行语句newManager(smith”)后程序的输出是哪项?()A.smithB.nullC.编译错误D.name

单项选择题 程序:classTestApp{intipublicstaticvoidmain(String[]args){for(inti=0;i<5;i++)System.out.print(i+1);System.out.println(i);(i没有定义)}}上述程序运行后的结果是哪项?()

单项选择题 Java语言中表达式-12>>3的结果是哪项?()(12的二进制00001100,-12的二进制11110100)

单项选择题 类Teacher:classTeacher{Stringname;floatsalary;Teacher(Stringname){this.name=name;}Teacher(Stringname,floatsalary){this.name=name;this.salary=salary;}}执行语句Teachert=newTeacher(Tom”,2000.0f);后,字段salary的值是哪一项?()A.2000.0fB.0.0fC.null;D.2000

单项选择题 类Student代码如下:DclassStudent{Stringname;intage;Student(Stringnm){(构造方法)name=nm;}}执行语句Studentstu=newStudent()后,字段age的值是哪项?()