Java程序設計第五章繼承、接口和抽象類程序閱讀題及答案

1、現(xiàn)有?publicclassParent{?publicvoidchange(intx){?}?}?publicclassChildextendsParent{?／／覆蓋父類change方法?}?下列哪個聲明是正確的覆蓋了父類的change方法？?A.publicvoidchange(intx){}B.protectedvoidchange(intx){}C.publicvoidchange(Strings){}D.publicvoidchange(intx,inty){}正確答案：A2、?classCa{ intnum=1; Ca(intnum){ this.num=num; System.out.print(this.num); }}classCbextendsCa{??intnum=2; Cb(intnum){ this.num=num;System.out.print(num);?? } publicstaticvoidmain(String[]args){ Caa=newCb(5); }}??運行代碼，程序輸出結果為：A.52B.51C.編譯報錯D.15正確答案：C3、?下面關于繼承的敘述正確的是（）A.Java類中只允許單一繼承B.Java中一個類不能同時繼承一個類和實現(xiàn)一個接口C.Java中一個類只能實現(xiàn)一個接口D.Java中一個類可繼承于多個類正確答案：A4、?給定下列程序，請選出正確結果。?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();?}?}?A.cablecat5B.cableC.cat5D.cat5cable正確答案：D5、?下列程序的輸出是（）。?classOther{?publicOther(){?System.out.print("Other!");? }?}??publicclassDriver1extendsOther{?publicstaticvoidmain(String[]args){?newDriver1();?newOther();?}?}?A.Other!Other!B.Other!C.Other!Other!Other!D.編譯出錯正確答案：A6、?請選出以下程序的輸出結果?classA{? publicvoidfunc1(){? System.out.println("Afunc1iscalling");? }?? publicvoidfunc2(){? func1();? }?}??classBextendsA{? publicvoidfunc1(){? System.out.println("Bfunc1iscalling");? }? publicvoidfunc3(){? System.out.println("Bfunc3iscalling");? }?}??classC{? publicstaticvoidmain(String[]args){?Aa=newB();?a.func1();?a.func2();?a.func3();? } ?}Afunc1iscallingBfunc3iscallingBfunc1iscallingBfunc3iscallingAfunc1iscallingAfunc1iscallingBfunc3iscallingD.編譯錯誤正確答案：D7、?請選出以下程序的輸出結果?publicclassChildextendsPeople{? Peoplefather;?? publicChild(Stringname){? System.out.print(3);? =name;? father=newPeople(name+":F");? }? publicChild(){? System.out.print(4);? }? publicstaticvoidmain(String[]args){? newChild("Alice");? }?}??classPeople{? Stringname;?? publicPeople(){? System.out.print(1);? }? publicPeople(Stringname){? System.out.print(2);? =name;? }?}A.123B.132C.32D.312正確答案：B8、?請選出正確答案?classParent{?Stringone,two;?publicParent(Stringa,Stringb){?one=a;?two=b;?}?publicvoidprint(){System.out.println(one);}?}??publicclassChildextendsParent{?publicChild(Stringa,Stringb){?super(a,b);?}??publicvoidprint(){?System.out.println(one+"to"+two);?}??publicstaticvoidmain(Stringarg[]){?Parentp=newParent("south","north");?Parentt=newChild("east","west");?p.print();?t.print();?}?}?southtonortheasttowestsoutheasttowestCauseerrorduringcompilation.D.southtonortheast正確答案：B9、?請選擇正確的輸出結果??classGuy{? publicGuy(){? System.out.print("111,");? }?}??classCowboyextendsGuy{? publicCowboy(){? System.out.print("222,");? }?}??classWranglerextendsCowboy{? publicWrangler(){? System.out.print("333,");? }?}?publicclassGreeting2{? publicstaticvoidmain(String[]args){? Guyg1=newGuy();? Guyg2=newCowboy();? Guyg3=newWrangler();? }?}?A.編譯錯誤B.111,111,222,111,222,333,C.111,111,222,222,333,D.111,222,333,正確答案：B10、?給定以下程序?classPencil{? publicvoidwrite(Stringcontent){? System.out.println("Write"+content);? }?}??classRubberPencilextendsPencil{? publicvoidwrite(Stringcontent){? System.out.println("RubberWrite"+content)；? }??publicv