简单的四则运算

public class Test {
    public static void res(){
        System.out.println("1.显示结果\t2.直接开始下一题");
    }
    public static void main (String[] arge){
        System.out.println("*****请选择要随机生成的算法*****");
        System.out.println("\t1,加法\t2,减法\t3,乘法\t4,除法");
        System.out.println("**********");
        Scanner sc=new Scanner(System.in);
        int s = sc.nextInt();
        double result=0;
        Random r = new Random();
        int a = r.nextInt(100);
        int b =r.nextInt(100);
        switch(s){
            case 1:System.out.println("-----|"+a+"+"+b+"=?|-----");result =a+b;res();break;
            case 2:System.out.println("-----|"+a+"-"+b+"=?|-----");result =a-b;res();break;
            case 3:System.out.println("-----|"+a+"*"+b+"=?|-----");result =a*b;res();break;
            case 4:System.out.println("-----|"+a+"/"+b+"=?|-----");{float c=a;float d=b;result=c/d;}res();break;
            default:System.out.println("输入有误，重新开始");main(null);break;
        }
        Scanner select =new Scanner(System.in);
        int se =select.nextInt();
        switch (se){
            case 1:System.out.println("本题的结果："+result);main(null);break;
            case 2:main(null);break;
            default:System.out.println("输入有误，重新开始");main(null);
        }
    }
}