四则运算v1.0

题目：

V1.0花二十分钟写一个能自动生成30道小学四则运算题目的 “软件”

V2.0题目避免重复；可定制（数量/打印方式）；

package Sizeyunsuan;
/**
 * 30道100以内四则运算
 * 
 * */
public class Random {

    public static int getRandom( int n, int m)
         {
        //产生n->m的随机数
                return (int) (Math.random() * (m - n) + n);
         }
    
    public static char getCharRandom()
    {
        //随机产生四种运算符
        char sign = 0;
        int Sn;
        Sn = getRandom(1,5);
        switch(Sn)
        {
            case 1:sign = '+' ;break;
            case 2:sign = '-' ;break;
            case 3:sign = '×' ;break;
            case 4:sign = '÷' ;break;
        }
        return sign;
    }
    
    public static void main(String[] args) {
        // TODO Auto-generated method stub

         int i = 0;
         do
         {
             int  x = (int) (Math.random() * (100 - 1 )+ 1);  //产生1-100的随机数
             int  y = (int) (Math.random() * (100 - 1 )+ 1);  //产生1-100的随机数
             char sign = getCharRandom();
             /*
              * 判断乘法的范围*/
             switch(sign)
             {
             case '+':
                 System.out.println( "("+ (i+1) +")"+ x + " " + sign + " " + y + "="     );
                 i++;break;
             case '-':
                 if(x < y)                        //判断减数与被减数的大小关系
                 {
                     int temp;
                     temp = x;
                     x = y;
                     y = temp;
                 }
                 System.out.println( "("+ (i+1) +")"+ x + " " + sign + " " + y + "="     );
                 i++;break;
             case '×':
             {
                 x = (int) (Math.random() * (10 - 1 )+ 1);//新生成x,y<9的随机数
                 y = (int) (Math.random() * (10 - 1 )+ 1);
                 
                     System.out.println( "("+ (i+1) +")"+ x + " " + sign + " " + y + "="     );    
                     i++;
             };break;
             case '÷':
                 do                                             //循环生成除法
                 {
                     y = (int) (Math.random() * (10 - 1 )+ 1);
                     x = (int) (Math.random() * (9*y - 1 )+ 1);
                                            
                 }
                while(x % y != 0) ;
                System.out.println( "("+ (i+1) +")"+ x + " " + sign + " " + y + "="     );
                i++;break;
                 }
        }
        while(i<30);
    }

}

完善后大概就是这样了，还有功能未完全实现