Java程序设计第五章继承、接口和抽象类程序阅读题及答案.docx

Is现有publicclassParetpublicvoidchange(intx)publicclassChildextendsParent/覆盖父类change方法)下列哪个声明是正确的覆盖了父类的change方法？A.publicvoidchange(intx)B.protectedvoidchange(itx)C.publicvoidchange(Strings)D.publicvoidchange(itx,inty)正确答案：A2、classCaintnum=1;Ca(itm)this.nur=num;System.out.prit(this.num);classCbextendsCaitnum=2;Cb(itnum)this.nur=num;System.out.prit(um);)publicstaticvoidmain(Strigargs)Caa=newCb(5);)运行代码，程序输出结果为：A.52B.51C.编译报错D.15正确答案：C3、下面关于继承的叙述正确的是()AJava类中只允许单一继承BJava中一个类不能同时继承一个类和实现一个接口CJava中一个类只能实现一个接口DJava中一个类可继承于多个类正确答案：A4、给定下列程序，请选出正确结果。classCatCat(itc)System.out.print("cat"+c+"");)classSubCatextendsCatSubCat(itc)super(5);System.out.print("cable");)SubCat()this(4)；)publicstaticvoidmain(String口args)SubCatS=newSubCat();)A.cablecat5B.cableC.cat5D.cat5cable正确答案：D5、下列程序的输出是()。classOtherpublicOther()System.ot.prit("Other!");)publicclassDriverlextendsOtherpublicstaticvoidmai(Stringargs)newDriverl();newOther();)A.0ther!0ther!B.Other!C.Other!Other!Other!D.编译出错正确答案：A6、请选出以下程序的输出结果classApublicvoidfcl()System.out.pritln(',Afundiscalling");)publicvoidfc2()fucl();)classBextendsApublicvoidfcl()System.out.pritln(',Bfundiscalling");)publicvoidfc3()System.out.pritln(',Bfuc3iscalling");)classCpublicstaticvoidmain(Strigargs)Aa=newBQ；a.fucl();a.fuc2();a.fuc3();)A. AfundiscallingBfc3iscallingB. BfundiscallingBfc3iscallingC. AfundiscallingAfundiscallingBfc3iscallingD.编译错误正确答案：D7、请选出以下程序的输出结果publicclassChildextendsPeoplePeoplefather;publicChild(Stringname)System.out.prit(3);this.ame=name;father=newPeople(name+":F");)publicChild()System.out.prit(4);)publicstaticvoidmain(Stringargs)newChild("Alice");)classPeopleStringname;publicPeopIeQSystem.out.prit(l);)publicPeople(Stringname)System.out.prit(2);this.ame=name;)A.123B.132C.32D.312正确答案：B8、请选出正确答案classParentStringone,two;publicParet(Striga,Stringb)one=a;two=b;publicvoidprint()System.ot.printl(oe);)publicclassChildextendsParentpublicChild(Stringa,Stringb)super(a,b);)publicvoidprit()System.out.pritln(oe+,to"+two);)publicstaticvoidmai(Stringarg)Parentp=newParet("south","north");Parentt=newChild(',east","west");p.print();t.prit();)A. southtonortheasttowestB. southeasttowestC. Causeerrorduringcompilation.D. D.southtonortheast正确答案：B9、请选择正确的输出结果classGuypublicGuy()System.out.prit(,llll");)classCowboyextendsGuypublicCowboy()System.out.prit("2221");)classWranglerextendsCowboypublicWragler()System.out.prit("333l");)publicclassGreeting2publicstaticvoidmain(Stringargs)Guygl=newGuy();Guyg2=newCowboy();Guyg3=newWrangler();)A.编译错误B.111,111,222,111,222,333,C.lll,111,222,222,333,D.llll222,333,正确答案：B10、给定以下程序classPencilpublicvoidwrite(Stringcontet)System.out.pritln("Write"+cotet);)classRubberPenciIextendsPecilpublicvoidwrite(Stringcontet)System.out.pritln(',RubberWrite"+cotet)；publicvoiderase(Stringcotet)System.ot.printl("Erase"+content);)执行下列代码的结果是哪项？Pencilp=ewPecil();(RubberPenciI)p).write(',Hello");A.RubberWriteHelloB.运行时抛出异常C.WriteHelloD.编译失败正确答案：B