如何在java中随机化字符“”和“-”

Question

我正在编写一个算术游戏，向用户提出一系列加法问题。但是，我想为每个问题随机分配一个运算符，以便问题可以是：

Question 1: num1 + num2 =

或

Question 2: num1 - num2 = 

我一直在用数学。random（）方法将num1和num2随机化我最不愿意做的事情是随机生成“”和“-”。

这是否与这两个字符的ASCII值有关，然后我可以在它们之间随机选择？谢谢你的帮助！

顺便说一句，我想让用户“按回车键”开始游戏，但我不知道如何操作。目前我让用户输入“y”开始。有什么想法吗？非常感谢。

//prompt user to start the game
            System.out.println();
            System.out.print("Press y to Start the Game: ");
            String start_program = keyboard.next();
    
            if (start_program.equals("y")) {

到目前为止，这是我的代码：

public static void main(String[] args) {
        //mental arithmetic game
        System.out.println("You will be presented with 8 addition questions.");
        System.out.println("After the first question, your answer to the previous question will be used\nas the first number in the next addition question.");

        //set up input scanner
        Scanner keyboard = new Scanner(System.in);


        //declare constant variables
        final int min_range = 1, max_range = 10, Max_Number_of_Questions = 8;

        long start_time, end_time;

        //generate 2 random numbers
        int random_number1 = (int) ((Math.random() * max_range) + min_range);
        int random_number2 = (int) ((Math.random() * max_range) + min_range);

        //declare variables
        int question_number = 1;
        int guess;


        //prompt user to start the game
        System.out.println();
        System.out.print("Press y to Start the Game: ");
        String start_program = keyboard.next();

        if (start_program.equals("y")) {


            //start timer
            start_time = System.currentTimeMillis();

            //ask the question
            System.out.print("Question " + question_number + ": What is " + random_number1 + " + " + random_number2 + "? ");
            //take in user input
            guess = keyboard.nextInt();


            while (guess == (random_number1 + random_number2) && question_number < Max_Number_of_Questions) {
                System.out.println("Correct");
                ++question_number;
                //generate a new question
                //generate 2 random numbers
                random_number1 = guess;
                random_number2 = (int) ((Math.random() * max_range) + min_range);
                //ask the question again
                System.out.print("Question " + question_number + ": What is " + random_number1 + " + " + random_number2 + "? ");
                //take in user input
                guess = keyboard.nextInt();
            }
            end_time = System.currentTimeMillis();
            int time_taken = (int) (end_time - start_time);

            if (guess != (random_number1 + random_number2))
                System.out.println("Wrong");
            else {
                System.out.println();
                System.out.println("Well Done! You answered all questions successfully in " + (time_taken / 1000) + " seconds.");
            }

        }
    }

Answer 1

“输入‘y’开始游戏”是完全多余的，当用户不输入‘y’时，你显然没有明智的事情要做就证明了这一点。

那么，既然这是一个命令行应用程序，为什么会有人启动它然后不想玩游戏呢？继续问第一个问题吧！如果用户确实以某种方式意外启动了该程序，那就不会有任何伤害，这并不是说您要覆盖重要文件、启动导弹或类似的东西。

Answer 2

我认为对于随机字符，您可以像这样使用布尔值：

Random rd = new Random(); // creating Random object
if(rd.nextBoolean()) { 
   //Do something 
} else { 
   //Do Something else
}

对于enter，我认为这是一个在ide控制台上玩的游戏？因为这样您就可以使用扫描仪跟踪按下enter键的时间。这将帮助您我想：Java使用扫描仪按enter键

Answer 3

您可以使用Random#nextInt从0到array.length-1选择一个随机int，您可以将其用作运算符数组的索引。

import java.util.Random;

public class Main {
    public static void main(String[] args) {
        char[] operators = { '+', '-', '*', '/' };

        // Pick a random operator
        Random random = new Random();
        char op = operators[random.nextInt(operators.length)];

        System.out.println(op);
    }
}

示例运行：

/