习题解答第一章作业题1．publicclassHello{publicstaticvoidmain(Stringargs[]){System.out.pintln(“早上好，goodMorning”);}}2．importjava.applet.*;importjava.awt.*;publicclassBoyextendsApplet{publicvoidpaint(Graphicsg){g.setColor(Color.blue);g.drawString("你好,hello",12,30);}}第二章作业题1．publicclassZuoYe2_1{publicstaticvoidmain(Stringargs[]){charc='а';System.out.println("字母"+c+"在unicode表中的顺序位置:"+(int)c);System.out.println("字母表：");while(c<='я'){System.out.print(""+c);c=(char)(c+1);}}}2．importjava.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+"个数的乘积为"+chengji);}}第三章作业题1．importjava.util.*;publicclassZuoYe3_1{publicstaticvoidmain(Stringargs[]){Scannerreader=newScanner(System.in);doubley=0,x=0;x=reader.nextDouble();if(x<0)y=-1+2*x;elseif(x==0)y=-1;elseif(x>0)y=-1+3*x;System.out.println(y);}}2．publicclassZuoYe3_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);}}3．publicclassZuoYe3_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);}}4．publicclassZuoYe3_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);}}5．publicclassZuoYe3_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);}}8．第四章作业题1．classDengCha{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));}}2．classLetter{publicvoidprintLetter(){for(charc='a';c<='z';c++)System.out.print(""+c);}}publicclassZuoYe4_2{publicstaticvoidmain(Stringargs[]){Letterp=newLetter();p.printLetter();}}3．classSquareEquation{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("是一元2次方程");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("方程的根:%f,%f\n",root1,root2);}else{System.out.printf("方程没有实根\n");}}else{System.out.println("不是一元2次方程");}}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();}}4．importjava.util.Scanner;classA{intf(intm,intn){if(m*n<0){System.out.println("有负数，程序退出");System.exit(0);}if(m
