JAVA大学实用教程(第三版)作业题答案

1publicclassHello{publicstaticvoidmain(Stringargs[]){System.out.pintln(goodMorning);}}2importjava.applet.*;importjava.awt.*;publicclassBoyextendsApplet{publicvoidpaint(Graphicsg){g.setColor(Color.blue);g.drawString(,hello,12,30);}}1publicclassZuoYe2_1{publicstaticvoidmain(Stringargs[]){charc='';System.out.println(+c+unicode:+(int)c);System.out.println();while(c=''){System.out.print(+c);c=(char)(c+1);}}}2importjava.util.*;publicclassZuoYe2_2{publicstaticvoidmain(Stringargs[]){Scannerreader=newScanner(System.in);longchengji=1;intm=0;while(reader.hasNextInt()){intx=reader.nextInt();m=m+1;chengji=chengji*x;}System.out.println(m++chengji);}}1importjava.util.*;publicclassZuoYe3_1{publicstaticvoidmain(Stringargs[]){Scannerreader=newScanner(System.in);doubley=0,x=0;x=reader.nextDouble();if(x0)y=-1+2*x;elseif(x==0)y=-1;elseif(x0)y=-1+3*x;System.out.println(y);}}2publicclassZuoYe3_2{publicstaticvoidmain(Stringargs[]){intsum=0,m=3,n=7,a=1;while(a=1000){if(a%m==0&&a%n==0)sum=sum+a;a++;}System.out.println(sum=+sum);}}3publicclassZuoYe3_3{publicstaticvoidmain(Stringargs[]){longsum=0,a=8,item=a,n=10,i=1;for(i=1;i=n;i++){sum=sum+item;item=item*10+a;}System.out.println(sum);}}4publicclassZuoYe3_4{publicstaticvoidmain(Stringargs[]){doublesum=0,a=1,b=1,fuhao=1,item=a/b;inti=1;while(i=1000){sum=sum+fuhao*item;i++;fuhao=fuhao*(-1);b=b+2;item=a/b;}System.out.println(sum=+sum);}}5publicclassZuoYe3_5{publicstaticvoidmain(Stringargs[]){doublesum=0,a=1;inti=1;while(i=20){if(i=10)sum=sum+a;i++;a=a*i;}System.out.println(sum=+sum);}}1classDengCha{intstart,d;DengCha(){}DengCha(intstart,intd){this.start=start;this.d=d;}voidsetStart(ints){start=s;}voidsetD(intd){this.d=d;}intgetSum(intn){intsum=0,i=1;while(i=n){sum=sum+start;start=start+d;i++;}returnsum;}}publicclassZuoYe4_1{publicstaticvoidmain(Stringargs[]){DengChashulie=newDengCha(2,3);System.out.println(shulie.getSum(100));shulie.setStart(10);shulie.setD(5);System.out.println(shulie.getSum(9));}}2classLetter{publicvoidprintLetter(){for(charc='a';c='z';c++)System.out.print(+c);}}publicclassZuoYe4_2{publicstaticvoidmain(Stringargs[]){Letterp=newLetter();p.printLetter();}}3classSquareEquation{doublea,b;staticdoublec;doubleroot1,root2;booleanboo;publicSquareEquation(doublea,doubleb,doublec){this.a=a;this.b=b;SquareEquation.c=c;if(a!=0){boo=true;}else{boo=false;}}publicvoidgetRoots(){if(boo){System.out.println(2);doubledisk=b*b-4*a*c;if(disk=0){root1=(-b+Math.sqrt(disk))/(2*a);root2=(-b-Math.sqrt(disk))/(2*a);System.out.printf(:%f,%f\n,root1,root2);}else{System.out.printf(\n);}}else{System.out.println(2);}}publicvoidsetCoefficient(doublea,doubleb,doublec){this.a=a;this.b=b;SquareEquation.c=c;if(a!=0){boo=true;}else{boo=false;}}}publicclassZuoYe4_3{publicstaticvoidmain(Stringargs[]){SquareEquationequation1=newSquareEquation(4,5,1);SquareEquationequation2=newSquareEquation(3,5,-7);equation1.getRoots();equation2.getRoots();}}4importjava.util.Scanner;classA{intf(intm,intn){if(m*n0){System.out.println();System.exit(0);}if(mn){inttemp=m;m=n;n=temp;}inta=m,b=n;intr=m%n;while(r!=0){m=n;n=r;r=m%n;}returnn;}}classB{Aa;B(){a=newA();}intg(intm,intn){inttemp=a.f(m,n);returnm*n/temp;}}publicclassZuoYe4_4{publicstaticvoidmain(Stringargs[]){Scannerreader=newScanner(System.in);System.out.println(2,);System.out.print(:);intm=reader.nextInt();System.out.print(:);intn=reader.nextInt();Aa=newA();Bb=newB();System.out.println(m++n++a.f(m,n));System.out.println(m++n++b.g(m,n));}}5importjava.applet.Applet;importjava.awt.*;publicclassExample4_10extendsApplet{Buttonredbutton;publicvoidinit(){redbutton=newButton();redbutton.setBackground(Color.red);redbutton.setForeground(Color.white);add(redbutton);}}1importjava.util.Scanner;classA{publicintf(intm,intn){if(mn){inttemp=m;m=n;n=temp;}intr=m%n;while(r!=0){m=n;n=r;r=m%n;}returnn;}}classBextendsA{publicintf(intm,intn){intdivision=super.f(m,n);return(m*n)/division;}}publicclassZuoYe5_1{publicstaticvoidmain(Stringargs[]){Aa=newA();Bb=newB();Scannerreader=newScanner(System.in);System.out.println(2,);System.out.print(:);intm=reader.nextInt();System.out.print(:);intn=reader.nextInt();if(m*n0){System.out.println();System.exit(0);}System.out.printf(%d%d%d\n,m,n,a.f(m,n));System.out.printf(%d%d%d\n,m,n,b.f(m,n));}}2abstractclassA{publicabstractvoidf(intx);publicabstractvoidg(intx,inty);publicabstractdoubleh(doublex);}classA1extendsA{publicvoidf(intx){System.out.println(x);}publicvoidg(intx,inty){intz=x+y;System.out.println(z);}publicdoubleh(doublex){returnx*x;}}classA2extendsA{publicvoidf(intx){System.out.println(Hello:+x);}publicvoidg(intx,inty){intz=x-y;System.out.println(z);}publicdoubleh(doublex){returnMath.sqrt(x);}}classA3extendsA{publicvoidf(intx){System.out.println(:+x);}publicvoidg(intx,inty){doublez=(double)x/y;System.out.println(z);}publicdoubleh(doublex){return1/x;}}publicclassZuoYe5_2{publicstaticvoidmain(Stringargs[]){Aa=newA1();a.f(10);a.g(12,20);System.out.println(a.h(100));a=newA2();a.f(10);a.g(12,20);System.out.println(a.h(100));a=newA3();a.f(10)