java程序设计课后第二章习题程序答案

1、习题9public class xiti9public static void main(String args)int x=4;int y;if(x<l)y=x;else if(x>=10)y=4*x;elsey=3*x-2;System.out.pri ntln(' ,y=,+y);习题12public class xitil2public static void main(String args)int sum=0;for(int k=l;k<=10;k+)sum=sum+k*k;System.out.println("sum="+sum);

2、习题13public class xitil3public static void main(String args)int t,a=3zb=5/c=8;if(a<b)t=a;a=b;b=t;if(a<c)t=a;a=c;c=t;if(bcc)7b;bHCoHs system.out.print-n(=>7、N一一 mEE-进" =+a+= =+b+= =+crMB 14 pub-ic c-ass xitil4 宀 pub-ic static void main(string args三 宀 int: nHl; system.outprint=nl,100 Z 亘&

3、#167;s*w»“ n=+= 3=)； for(intiulAH100;i+)宀 forTt: j=2AHi、2;j+) 宀if (求HHO)(breakssystem.out.print(=+i)； n+ system.outprint-n(=n*4-+n+-4。M圄 15 pub=c dass xitil5 宀 pub-ic static void main(string argsu) 宀 in- i、r for(ll'l;A10;i+) 宀 for(li-l;A'l.;j+) 宀 system.out.print(i+=:+j+”+*j+=)；system.o

4、ut.print-n()；习题16public class xitil6public static void main(String args)int a=3,124,7,6,5,9,8;int min=a0/max=a0/t/i/j;for(i=l;i<a.length;i+)if(min>ai)min=ai;if(max<ai)max=ai;System.out.println("nmax=,+max+"/min="+min);for(i=0;i<aength;i+)for(j=i+l;j<a.le ngth;j+)if 何 i&

5、gt;aj)t=ai;ai=aj;aj=t;System.out.print("n数组从小到大排序为：")； for(i=0;i<aength;i+)System.out.print(ai+"")；System.out.println();习题17public class xitil7_lpublic static void main(String args)int ij；for(i=0;i<4;i+)for(j=0;j<=i;j+)System.out.print("#")；System.out.println()

6、;public class xitil7_2public static void main(String args)char D=new char47;int i,j,a=3;for(i=0;i<4;i+)for(j=a;j>=0;j-)Di3-j*；Di3+j"a-；for(i=0;i<4;i+)for(j=0;j<7;j+)System.out.print(Dij);System.out.println();public class xitil7_3public static void main(String args)char D=new char; i

7、nt i,j,a=l;for(i=0;i<5;i+)if(i<3) 上三行数组元素赋值。for(j=0;j<=i;j+)Di2-j=，$'；Di2+jF$；else 下两行数组元素赋值。 for(j=a;j>=0;j-)Di2-j=,$,；Di2+j=$'；a-； for(i=0;i<5;i+) 数组元素输出，显示结果。for(j=0;j<5;j+)System.out.print(Dij);System.out.printlnf);习题19public class xitil9public static void main(String a

8、rgs)int D=new int；int i,j,k=O;System.out.println(''数组为:")； for(i=0;i<3;i+) 数组元素赋初值。for(j=0;j<3;j+)Dij=k;System.out.print(Dij);k+;System.out.pri ntln();int suml=0,sum2=0;for(i=0J=0;i<3;i+J+)suml=suml+Dij；for(i=OJ=2;i<3;i+J-)sum2=sum2+Dij;System.out.println("n主对角线元素之和suml

9、="+suml+"n副对角线元素之和 sum2=,+sum2);习题20public class xiti20public static void main(String args)int nJ;Stri ng sl=,afeidavabceidj,/s2="abcH;System.out.println(Hn 字符串为:"+sl);byte d=sl.getBytes();for(n=0;n<sl.length()-3;n+)String s二new String(d,n/3)；i=pareTo(s2);if(i=0)System.out.pri

10、ntln("n 字符串中包含有 “abc” ！")；break;if(n=sl.length()-3)System.out.println("n 字符串中不包含 “abc” ！")；习题21import java.util.*;public class xiti21public static void main(String args)int i,nl=0,n2=0;chara=,a7A7b,；B7c,；C,；d,；D,；e,；E,；f,；F,；g,；G,;char b=new char10;char c=new char10;for(i=0;i<

11、aen gth;i+)if(ai>=65 && ai<=90)bnl=ai; nl+;if(ai>=97 && ai<=122)cn2=ai;n2+;System.out.print(Hn 大写字母有：")； for(i=0;i<nl;i+)System.out.print(bi);System.out.println();System.out.print("n 小写字母有:");for(i=0;i<n2;i+)System.out.pri nt(ci);System.out.println();习题22import java.util.*;public class xiti22public static void main(String args)String s=,l Love you!"StringTokenizer st=new