数学测验的随机运算符 [重复]

Question

我正在尝试生成随机运算符以使随机问题具有随机运算符，请帮助

public void generateNewAddQuestion () {
        Random rand = new Random();
        int a = rand.nextInt(21);
        int b = rand.nextInt(21);
        int c =0;

        sumTextView.setText(Integer.toString(a) + "+" + Integer.toString(b));
        locationOfCorrecAnswer = rand.nextInt(4);
        answers.clear();
        String[] operators = {"+", "-", "x", "/"};

        int incorrectAnswer;

        for (int i=0; i < 4; i++) {
            if (i == locationOfCorrecAnswer) {
                answers.add(a+b);
                sumTextView.setText(Integer.toString(a)+"+"+Integer.toString(b));
            }
            else {
                incorrectAnswer = rand.nextInt(41);
                while(incorrectAnswer == a+b) {
                    incorrectAnswer = rand.nextInt(41);
                }
                answers.add(incorrectAnswer);
            }
        }
        button2.setText(Integer.toString(answers.get(0)));
        button3.setText(Integer.toString(answers.get(1)));
        button4.setText(Integer.toString(answers.get(2)));
        button5.setText(Integer.toString(answers.get(3)));
    }

Answer 1

您需要使用operators[rand.nextInt(4)] 来获取随机运算符，例如

import java.util.Random;

public class Main {
    public static void main(String[] args) {
        String[] operators = { "+", "-", "x", "/" };
        Random rand = new Random();
        System.out.println(operators[rand.nextInt(4)]);
    }
}

如果您执行此代码，它将每次打印一个随机运算符。

[更新]

这就是您需要在程序中使用该解决方案的方式：

String[] operators = {"+", "-", "x", "/"};
int oprIndex = rand.nextInt(4);
sumTextView.setText(Integer.toString(a) + operators[oprIndex] + Integer.toString(b));

稍后在您的程序中，您将需要使用oprIndex 来查找已将哪个运算符设置为sumTextView，然后您可以执行相应的算术运算，例如

switch (operators[oprIndex]) {
case "+":
    System.out.println("Pocessing addition");
    break;
case "-":
    System.out.println("Pocessing subtraction");
    break;
case "x":
    System.out.println("Pocessing multiplication");
    break;
case "/":
    System.out.println("Pocessing division");
    break;
}