java重点程序.doc

4.1import java.util.Scanner;public class Exercise4_1public static void main(Stringargs)int positive =0,negative=0,count=0,sum=0,num;Scanner input = new Scanner(System.in);System.out.print(Enter an int value, the program exits if the input is 0:);num = input.nextInt();while (num!=0)if (num0)positive+;elsenegative+;sum+=num;count+;num=input.nextInt();System.out.println(The number of positive is +positive);System.out.println(The number of negative is +negative); System.out.println(The sum is +sum); System.out.println(The average is +sum*1.0/count); 4.19Public class ex419public static void main (String args)for(int i=1;i=8;i+)for(int j=1;j=8-i;j+)System.out.print( );for(int k=1;k=1;k-)System.out.printf( %3d,(int)Math.pow(2,k-1);System.out.println();5.3import java.util.Scanner;public class Exercise5_3public static void main(String args)Scanner input=new Scanner (System.in);System.out.println(Enter a postive integer:);int number=input.nextInt();if (isPalindrome(number)System.out.println(number+ is palindrome);elseSystem.out.println(number+ is not palindrome);public static boolean isPalindrome(int number)return (number=reverse(number);public static int reverse (int number)int result =0;while (number!=0)int remainnumber = number%10;result=result*10+remainnumber;number=number/10;return result;5.14import java.util.Scanner;public class countpublic static void main(String args)for(int i = 10 ; i = 100 ; i += 10 )a(i); public static void a ( int i )double k = 1,sum = 0;for ( double t = 1 ; t ( 2 * i + 1 ) ; t += 2 ) sum += ( ( 1/t ) * k );k= - k;System.out.printf(%-5d%.5fn,i,sum*4);6.5import java.util.Scanner;public class pr65public static void main(String args )System.out.print(enter 10 numbers: );int mylist=new int10;int i,j;Scanner input=new Scanner (System.in);for(i=0;i10;i+)mylisti=input.nextInt();System.out.print(the distinct numbers are: );for(i=0;i10;i+)for(j=i+1;js2.length() return false;else for(int i=0,k; is2.length() ;i+)if(s2.charAt(i)=s1.charAt(0)for (k=1; k(s2.length()-i)&k=8)for(m=0;m=s.length()-1;m+)if(s.charAt(m)57&s.charAt(m)122) break; if (s.charAt(m)47&s.charAt(m)58)number+;if(number2)return a;elsea=true; return a;public class Test8_1public static void main(String args)Rec rec1 = new Rec (4,40);Rec rec2 = new Rec (3.5,35.9);System.out.println(矩形1宽: +rec1.width+ 高: +rec1.height+ 面积: +rec1.getArea()+ 周长: +rec1.getPerimeter();System.out.println(矩形2宽: +rec2.width+ 高: +rec2.height+ 面积: +rec2.getArea()*100/100+ 周长: +rec2.getPerimeter();static class Recdouble width , height ;Rec()width = 1;height = 1;Rec( double Width ,