java - 编写一个带有随机数的程序

Question

我必须为我的 CS 入门类(class)编写一个程序作为一个项目。该程序必须

1. 询问用户最小值(可以为负数)
2. 询问用户最大值(也可以是负数，但必须大于最小值)
3. 生成 20 个介于用户给出的最小/最大值之间的随机数
4. 生成二十个随机数的平均值。

我以为我已经完成了程序，但当我执行程序时，数字从来都不是随机的，所有二十个数字都与我输入 emacs 的最大值相同。当然，在这种情况下平均值也与最大值相同。这是我到目前为止的程序...

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

public class CS_ProjectOne
{
    public static void main(String[] args)
    {
    int minimum_integer;
    int maximum_integer;
    int rn1;
    int rn2;
    int rn3;
    int rn4;
    int rn5;
    int rn6;
    int rn7;
    int rn8;
    int rn9;
    int rn10;
    int rn11;
    int rn12;
    int rn13;
    int rn14;
    int rn15;
    int rn16;
    int rn17;
    int rn18;
    int rn19;
    int rn20;
    double total;
    double average;
    Scanner keeper;
    Scanner keeper2;
    Random gen;
    gen = new Random();

    keeper = new Scanner(System.in);
    System.out.print("Please enter an integer for the MINIMUM value: ");
    minimum_integer = keeper.nextInt();

    keeper2 = new Scanner(System.in);
    System.out.print("Please enter an integer for the MAXIMUM value: ");
    maximum_integer = keeper2.nextInt();

    rn1 = gen.nextInt();
    rn1 = rn1 % minimum_integer + maximum_integer;
    rn2 = gen.nextInt();
    rn2 = rn2 % minimum_integer + maximum_integer;
    rn3 = gen.nextInt();
    rn3 = rn3 % minimum_integer + maximum_integer;
    rn4 = gen.nextInt();
    rn4 = rn4 % minimum_integer + maximum_integer;
    rn5 = gen.nextInt();
    rn5 = rn5 % minimum_integer + maximum_integer;
    rn6 = gen.nextInt();
    rn6 = rn6 % minimum_integer + maximum_integer;
    rn7 = gen.nextInt();
    rn7 = rn7 % minimum_integer + maximum_integer;
    rn8 = gen.nextInt();
    rn8 = rn8 % minimum_integer + maximum_integer;
    rn9 = gen.nextInt();
    rn9 = rn9 % minimum_integer + maximum_integer;
    rn10 = gen.nextInt();
    rn10 = rn10 % minimum_integer + maximum_integer;
    rn11 = gen.nextInt();
    rn11 = rn11 % minimum_integer + maximum_integer;
    rn12 = gen.nextInt();
    rn12 = rn12 % minimum_integer + maximum_integer;
    rn13 = gen.nextInt();
    rn13 = rn13 % minimum_integer + maximum_integer;
    rn14 = gen.nextInt();
    rn14 = rn14 % minimum_integer + maximum_integer;
    rn15 = gen.nextInt();
    rn15 = rn15 % minimum_integer + maximum_integer;
    rn16 = gen.nextInt();
    rn16 = rn16 % minimum_integer + maximum_integer;
    rn17 = gen.nextInt();
    rn17 = rn17 % minimum_integer + maximum_integer;
    rn18 = gen.nextInt();
    rn18 = rn18 % minimum_integer + maximum_integer;
    rn19 = gen.nextInt();
    rn19 = rn19 % minimum_integer + maximum_integer;
    rn20 = gen.nextInt();
    rn20 = rn20 % minimum_integer + maximum_integer;

    System.out.println("Your random numbers are: " + rn1 + ", " + rn2 + ", " + rn3 + ", " + rn4 + ", " + rn5 + ", " + rn6 + ", " + rn7 + ", " + rn8 + ", " + rn9 + ", " + rn10 + ", " + rn11 + ", " + rn12 + ", " + rn13 + ", " + rn14 + ", " + rn15 + ", " + rn16 + ", " + rn17 + ", " + rn18 + ", " + rn19 + ", " + rn20 + ".");

    total = rn1 + rn2 + rn3 + rn4 + rn5 + rn6 + rn7 + rn8 + rn9 + rn10 + rn11 + rn12 + rn13 + rn14 + rn15 + rn16 + rn17 + rn18 + rn19 + rn20;
    average = total / 20;

    System.out.print("The average is " + average);
    }
}

有人可以提供帮助并引导我走向正确的方向吗？我确信我有些事情做得不正确(或者很多事情)，我只是不知道那到底是什么。

这是我试图让它发挥作用的简短版本...

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

public class p1
{
    public static void main(String[] args)
    {
    Random gen;
    gen = new Random();
    Scanner keeper;
    int range, user_min, user_max, num1, num2, num3, total;
    double average;

    keeper = new Scanner(System.in);
    System.out.print("Please enter a maximum integer value: ");
        user_max = keeper.nextInt();

        keeper = new Scanner(System.in);
    System.out.print("Please enter a minimum integer value: ");
    user_min = keeper.nextInt();

    range = user_max - user_min + 1;

    num1 = gen.nextInt() % range + user_min;
    num2 = gen.nextInt() % range + user_min;
    num3 = gen.nextInt() % range + user_min;

    System.out.print("The random numbers computed are " + num1 + ", " + num2 + ", " + num3 + ", ");
    }
}

为什么这不能处理负数？我的值仍然不在指定范围内？帮忙吗？

Answer 1

一些技巧/提示:

1. 使用一个数组来存储 20 个数字。这样，当你发现错误时，你只需纠正一次，而不是 20 次。

2. 随机数生成器有种子。确保您每次提供不同的种子，否则您的随机数生成器将始终生成相同的随机数集。

3. MIN 和 MAX 之间可以有多少个值？例如，3 到 7 之间可以有多少个不同的值？ 45和80？ 3和1200？找到规律。

4. 了解为什么您的程序需要“%”运算符。通过执行“gen.nextInt() % NUM”可以实现什么目的？