随机加减乘除运算器

/**
随机加减乘除运算器，要求如下:程序依次出 10 道题目，由用户输入题目的答案。用户
每答完一道题，由系统提示结果：答错了或者答对了。10 道题目答完之后，系统计算得分
并输出。如果用户希望提前结束，则可以输入－1提前退出。


-------------------------------------
 */
public class MathTest {
    /*定义静态常量 为下面的switch做准备*/
    public static final int ADD = 0;
    public static final int SUB = 1;
    public static final int MULTI = 2;
    public static final int DIV = 3;
    //除法不准确,想准确需要都换成double类型

    public static void main(String[] args) {

        System.out.println("随机加减乘除运算器,程序启动");
        operation();
    }

    public static void operation() {
        Scanner scan = new Scanner(System.in);
        Random random = new Random();
        int score = 0;
        for(int i =0; i<10; i++){
            int num1 = random.nextInt(10);
            int num2 = random.nextInt(10)+1;    //加1避免除数是0的情况
            int sum = 0;
            int answer ;
            int type = random.nextInt(4);    //随机生成加减乘除4种选择
            switch(type){
            case ADD:
                sum = num1+num2;
                System.out.println("["+(i+1)+"] "+num1+"+"+num2+" = ?");
                break;
            case SUB:
                sum = num1-num2;
                System.out.println("["+(i+1)+"] "+num1+"-"+num2+" = ?");
                break;
            case MULTI:
                sum = num1*num2;
                System.out.println("["+(i+1)+"] "+num1+"*"+num2+" = ?");
                break;
            case DIV:
                sum = num1/num2;
                System.out.println("["+(i+1)+"] "+num1+"/"+num2+" = ?");
                break;
            }
            System.out.println("请输入答案:");
            answer = scan.nextInt();

            if(answer == sum){
                System.out.println("答对,得分:"+(score+=10));
            }else if(answer == -1){
                System.out.println("退出游戏");
                break;
            }else{
                System.out.println("答错,下一题");
            }
        }
    }
}