四则运算

package zuoye;

 import java.util.*;
 public class Test {
 public static String yuefen(int a,int b){
         int y = 1;
         for(int i=a;i>=1;i--){
            if(a%i==0&&b%i==0){
                y = i;
               break;
             }           
        }
        int z = a/y;
        int m = b/y;
      if(z==0) {
             return "0";
        }
        return ""+z+"/"+m;
     }
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int x,y,i,a1;
        int d1=0;
        String d = null;
       System.out.println("1、整数计算式");
       Scanner scan1=new Scanner(System.in);
        a1=scan1.nextInt();
if(a1==1){
        System.out.println("请输入题目的数量");
        Scanner scan2=new Scanner(System.in);
        x=scan2.nextInt();
        int daan[]=new int [x];
         System.out.println("请输入数值的范围");

         y=scan2.nextInt();
        for(i=0;i<x;i++){
            int a=(int)(Math.random()*y);
           int b=(int)(Math.random()*y);
             int c=(int)(Math.random()*3);
           if(c==0)
           {
                d1=a+b;
              System.out.print(a+"+"+b+"=       ");
             }
             if(c==1)
            {
            d1=a-b;
               System.out.print(a+"-"+b+"=       ");
             }
            if(c==2)
            {
                 d1=a*b;
                System.out.print(a+"*"+b+"=       ");
            }
             if(c==3)
             {
                 d1=a/b;
                 System.out.print(a+"/"+b+"=       ");
             }
             if((i+1)%3==0){
                 System.out.println();
             }
             daan[i]=d1;
        }
         System.out.println("是否显示答案（显示请输入1）");
         if(scan2.nextInt()==1){
             for(i=0;i<x;i++){
             System.out.print(daan[i]+"     ");
             }
         }
         }

}