四则运算 测试与封装5.1

package test1;

import java.util.*;
public class Si {
 
    /**
     * @param args
     */
    public static void main(String[] args) {
        int a=0,b=0;
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入你的题量；");
        int c=sc.nextInt();
        
        Feng feng = new Feng();
        feng.calc(c, a, b);
    }    
}
package test1;
import java.util.Scanner;
public class Feng {
    public void calc(int c, int a, int b) {
        Scanner sc = new Scanner(System.in);
        for(int i=0;i<c;i++)
        {
        int s=1+(int)(Math.random()*4);
        switch(s)
        {
        case 1:
                int k;
                a=1+(int)(Math.random()*100);
                b=1+(int)(Math.random()*100);
                System.out.println(a+"+"+ b + "=");
                k=sc.nextInt();
                if(k==a+b)
                    System.out.println("答案正确；");
                else System.out.println("答案错误,正确答案为"+(a+b));   
                break;
        case 2:
            int l=0;
            a=1+(int)(Math.random()*100);
            b=1+(int)(Math.random()*100);
            System.out.println(a+"-"+ b + "=");
            l=sc.nextInt();
            if(l==a-b)
            {
                System.out.println("答案正确；");
                if(a<b)
                    System.out.println("改答案为负数；");
            }
            else System.out.println("答案错误,正确答案为"+(a-b));   
            break;
        case 3:
            int m;
            a=1+(int)(Math.random()*10);
            b=1+(int)(Math.random()*10);
            System.out.println(a+"*"+ b + "=");
            m=sc.nextInt();
            if(m==a*b)
                System.out.println("答案正确；");
            else System.out.println("答案错误,正确答案为"+(a*b));   
            break;
        case 4:
                int n;
                a=1+(int)(Math.random()*10);
                b=1+(int)(Math.random()*10);
                System.out.println(a+"/"+ b + "=");
                n=sc.nextInt();
                if(n==a/b)
                    System.out.println("答案正确；");
                else System.out.println("答案错误,正确答案为"+(a/b));   
                break;
            }
        }
    }
}

模仿助教的方法，不知道对不对！！！！！