java复习资料 7页

1、阅读以下程序，输出结果为classQ1{publicstaticvoidmain(Stringargs[]doubled=1.23;Decdec=newDec();dec.decrement(d);System.out.println(d);}classsDec{publicvoiddecrement(doubledecMe){decMe=decMe—0.1;}}2、以下程序段的输出结果为。classCruncher{voidcrunch(inti){System.out.println("intversion");}voidcrunch(Strings){System.out.println("Stringversion");}publicstaticvoidmain(Stringargs[]){Crunchercrun=newCruncher();charch='p';crun.crunch(ch);}}3、阅读以下程序段：classParent{voidprintMe(){System.out.println("pt");}}classChildextendsParent{voidprintMe(){System.out.print("cd");}voidprintAll(){super.printMe();this.printMe();printMe();}publicclassTest_this{publicstaticvoidmain(Stringargs[]){ChildmyC=newChild();myC.printAll();}}输出结果为。4、已有Bird类的定义如下：packageabcde;7/8\npublicclassBird{protectedstaticintreferenceCount=0;publicBird(){referenceCount++;}protectedvoidfly(){}staticintgetReCount(){returnreferenceCount;}}有类Nightingale的定义如下，请写出它的输出结果packagesingers；classNightingaleextendsabcde.Bird{Nightingale(){referenceCount++;}publicstaticvoidmain(Stringargs[]){System.out.print("Before:"+referenceCount);Nightingaleflorence=newNightingale();System.out.println("After:"+referenceCount);florence.fly();}}5、以下程序段的输出结果为。publicclasstest{publicstaticvoidmain(Stringargs[]){StringBuffers=newStringBuffer("Hello");s.append("there");System.out.println(s);Stringpf=s.substring(0,s.length());System.out.println(pf.equals("Hellothere"));}}6、以下程序段的输出结果为。classPerson{publicPerson(){System.out.println("hi!");}publicPerson(Strings){this()；System.out.println("Iam"+s);}}publicclassWhoextendsPerson{publicWho(){this("IamTony");}publicWho(Strings){super(s);System.out.println("Howdoyoudo?");7/8\n}publicstaticvoidmain(Stringargs口儿Whow=newWho("Tom");}}7.下面是一个类的定义。class//定义名为MyClass的类{intvar=666;staticintgetvar(){returnvar;}}8.以下程序的输出结果为publicclassabc{publicstaticvoidmain(Stringargs[]){SubSubClassx=newSubSubClass(10,20,30);x.show();}}classSuperClass{inta,b;SuperClass(intaa,intbb){a=aa;b=bb;}voidshow(){System.out.println("a="+a+"\nb="+b);}}classSubClassextendsSuperClass{intc;SubClass(intaa,intbb,intcc){super(aa,bb);c=cc;}}classSubSubClassextendsSubClass{inta;SubSubClass(intaa,intbb,intcc){super(aa,bb,cc);a=aa+bb+cc;}voidshow(){System.out.println("a="+a+"\nb="+b+"\nc="+c);}}9.以下程序的输出结果为classPerson{publicPerson(){System.out.println("Person");}}classStudentextendsPerson{publidStudent。7/8\n{System.out.println("Student");}}classCollegeStudentextendsStudent{publicCollegeStudent(){System.out.println("CollegeStudent");}publicclassTest{publicstaticvoidmain(String口args){CollegeStudentcs=newCollegeStudent();}}10.通过键盘输入10个整数，并按输入的倒序输出这10个整数。importjava.io.*;publicclassReverse{publicstaticvoidmain(Stringargs口){inti,n=10;inta[]=newint[10];for(i=0;i=0;i--)System.out.print(a[i]+"");System.out.println();}}11.以下程序的输出结果为。publicclassEqualOrNot{publicstaticvoidmain(Stringargs口){Bb1=newB(5);Bb2=newB(5);System.out.println(b1==b2);System.out.println(b1.equals(b2));}}classB{intx;B(inty){x=y;}}12.以下程序的输出结果为。classParent{voidprintMe(){System.out.println("parent");}}classChildextendsParent{voidprintMe(){System.out.println("child");}voidprintAll(){super.printMe();this.printMe();printMe();}b}publicclassTest_this{publicstaticvoidmain(Stringargs[]){ChildmyC=newChild();myC.printAll();}}13.以下程序的输出结果为classCruncher7/8\n{voidcrunch(inti){System.out.print("int");}voidcrunch(Strings){System.out.print("String");}publicstaticvoidmain(Stringargs[])7/8\nCrunchercrun=newCruncher();charch='h'；inti=12;crun.crunch(ch);System.out.print(=”);crun.crunch(i);}}14.阅读以下程序：importjava.io.*;publicclassAboutFile{publicstaticvoidmain(String[]args){BufferedReaderb=newBufferedReader(newInputStreamReader(System.in));Strings;System.out.flush();try{s=b.readLine();System.out.println("Stringis:"+s);}Catch(IOExceptione){System.out.println(e.getMessage());}}运行以上程序，若从键盘输入：java＜回车〉则输出结果为15.写出以下程序的运行结果。publicclass{TryCatchFinally7/8staticvoidProc(intsel){try{if(sel==0){System.out.println("noException");return;i=0;intj=4/i;}}elseif(sel==1){int}catch(ArithmeticExceptione){System.out.println("Catch");}catch(Exceptione){System.out.println("Willnotbeexecuted");}finally{System.out.println("finally");}}publicstaticvoidmain(Stringargs口){Proc(0);Proc(1);}}输出结果为：15.阅读以下程序，写出输出结果。classAnimal{Animal(){System.out.print("Animal");}}publicclassDogextendsAnimal{Dog(){System.out.print("Dog");}publicstaticvoidmain(String口args){Dogsnoppy=newDog();}}输出结果为：。编程题1、编写一个类，要求该类实现一个接口，该接口有3个abstract方法：7/8\npublicabstractvoidf(intx);publicabstractvoidg(intx,inty);publicabstractdoubleh(doublex);要求在应用程序的主类中使用该类创建对象，并使用接口回调来调用方法：f(),g()和h()。2、创建一个窗体，窗体中有一个按钮btn,二个文本框txt1和txt2。当单击按钮后，第一个文本框的内容会显示在第二个文本框当中。3.编写一个应用程序，设计4个按钮，分别命名为“加”、“减”、“乘”、“除”，有3个文本框。单击相应的按钮，将两个文本框的数字做运算，在第三个文本框中显示结果。4.编写程序，完成文件复制功能，即将a.txt文件内容复制到b.txt文件中去。567/8