9.19随笔

用Java实现一个程序：

随机生成30道小学二年级的四则运算，要求：减法结果不可出现负数，除法结果不可出现小数，乘法结果不能超过999.

代码如下：

import java.util.Random;
import java.util.Scanner;

public class ArithmeticQuiz {
    public static void main(String[] args) throws InterruptedException {
        Scanner scanner = new Scanner(System.in);
        Random random = new Random();

        int correctCount = 0;
        int wrongCount = 0;

        for (int i = 0; i < 30; i++) {
            int operand1 = generateNumber(10, 99, random);
            int operand2 = generateNumber(10, 99, random);
            char op = generateOperator(random);

            int result = 0;
            String operatorStr;

            switch (op) {
                case '+':
                    result = operand1 + operand2;
                    operatorStr = "+";
                    break;
                case '-':
                    if (!checkSubtraction(operand1, operand2)) {
                        i--;
                        continue;
                    }
                    result = operand1 - operand2;
                    operatorStr = "-";
                    break;
                case '*':
                    if (!checkMultiplication(operand1, operand2)) {
                        i--;
                        continue;
                    }
                    result = operand1 * operand2;
                    operatorStr = "*";
                    break;
                case '/':
                    if (!checkDivision(operand1, operand2)) {
                        i--;
                        continue;
                    }
                    result = operand1 / operand2;
                    operatorStr = "/";
                    break;
                default:
                    operatorStr = "";
                    break;
            }

            System.out.println("倒计时开始！请在10秒内回答问题！");
            System.out.print("题目" + (i + 1) + ": " + operand1 + " " + operatorStr + " " + operand2 + " = ");
            int answer = scanner.nextInt();

            Thread timerThread = new Thread(new TimerThread());
            timerThread.start();

            timerThread.join(10000);
            timerThread.interrupt();

            if (answer == result) {
                System.out.println("回答正确！");
                correctCount++;
            } else {
                System.out.println("回答错误！");
                wrongCount++;
            }
        }

        System.out.println("回答正确的题目数量: " + correctCount);
        System.out.println("回答错误的题目数量: " + wrongCount);
    }

    public static int generateNumber(int min, int max, Random random) {
        return min + random.nextInt(max - min + 1);
    }

    public static char generateOperator(Random random) {
        char[] operators = {'+', '-', '*', '/'};
        int index = random.nextInt(4);
        return operators[index];
    }

    public static boolean checkSubtraction(int operand1, int operand2) {
        return operand1 >= operand2;
    }

    public static boolean checkMultiplication(int operand1, int operand2) {
        return operand1 * operand2 <= 999;
    }

    public static boolean checkDivision(int operand1, int operand2) {
        return operand1 % operand2 == 0;
    }
    static class TimerThread implements Runnable {
        @Override
        public void run() {
            for (int i = 0; i >= 0; i--) {
                if (Thread.interrupted()) {
                    return;
                }
                System.out.println("剩余时间: " + i + "秒");
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    return;
                }
            }
            if (!Thread.interrupted()) {
                System.out.println("时间到！");
            }
        }
    }

}
//在倒计时的时候顺序有点错误