Java Math.random 返回 0？

Question

我知道这个问题之前已经回答过，我看过这里：math.random, only generating a 0? 以及其他一些论坛，但到目前为止一直无法回答我的问题。

我正在尝试为石头剪刀布游戏生成 1 到 3 之间的随机数（包括 1 和 3）。不幸的是，我的随机数的输出总是 0。

请注意，我不允许使用 Random();类，并且必须使用 Math.random 方法来实现这一点。这是我的随机数代码：

  public static int randomComputerChoice(int highVal, int lowVal) {
         do{
             highVal = 4;
             lowVal = 0;
     computerChoice=0;//resets random number
   //generates and returns a random number within user's range 
     computerChoice = (int)((Math.random()* highVal)+1);
     } while((computerChoice>= highVal)||(computerChoice<= lowVal));
     return (computerChoice);
} 

}

我不确定这是否有必要，但我觉得错误可能出现在我的其余代码中。

import java.util.Scanner;
import java.io.IOException;

public class RockPaperScissors {

    static int weaponChoice;
    static int computerChoice;
   static int lowVal = 1;
   static int highVal = 3;

    /**
     * @param args the command line arguments
     * @throws java.io.IOException
     */
    public static void main(String[] args) throws IOException {
        Scanner userInput = new Scanner(System.in);
        System.out.println(" =========================");
        System.out.println("====ROCK=PAPER=SCISSORS====");
        System.out.println(" =========================");
        int playAgain = 1; //sets a play again function
       do {
            System.out.println("Please select your weapon.");
            System.out.println("1 - Rock");
            System.out.println("2 - Paper");
            System.out.println("3 - Scissors");
            System.out.println("Choose wisely:");
            String choice = userInput.nextLine();
            weaponChoice = Integer.parseInt(choice);
            do {
           if (weaponChoice != 1 && weaponChoice != 2 && weaponChoice != 3) {
                    System.out.println("Please choose again, grasshopper. There are only"
                        + " three choices.");
                System.out.println("1 - Rock");
                System.out.println("2 - Paper");
                System.out.println("3 - Scissors");
                choice = userInput.nextLine();
                weaponChoice = Integer.parseInt(choice);
            }
            } while (weaponChoice != 1 && weaponChoice !=2 && weaponChoice != 3);

            if (weaponChoice == 1) {
                System.out.println("You have selected Rock as your weapon.");
            }
            else if (weaponChoice == 2) {
                System.out.println("You have selected Paper as your weapon.");
            }
            else {
                System.out.println("You have selected Scissors as your weapon.");
            }
            //Computer's Choice
             System.out.println("The computer's choice is "+computerChoice);


        } while (playAgain == 1);
}

   public static int randomComputerChoice(int highVal, int lowVal) {
         do{
             highVal = 4;
             lowVal = 0;
     computerChoice=0;//resets random number
   //generates and returns a random number within user's range 
     computerChoice = (int)((Math.random()* highVal)+1);
     } while((computerChoice>= highVal)||(computerChoice<= lowVal));
     return (computerChoice);
} 


} 

感谢您的帮助！非常感谢。

Answer 1

尝试： Min + (int)(Math.random() * ((Max - Min) + 1))。输出应该是 1 到 3 之间的数字。 最小填1，最大填3。就是这样。那么数字范围应该是：[1,3]，这意味着包括 1 AND 3。

这里有另一个建议：

int number = 1 + (int)(Math.random() * ((3 - 1) + 1));
    System.out.println(number);
//alternative way:
// return number;