java中的骰子模拟答案

【问题标题】：Dice simulation in javajava中的骰子模拟
【发布时间】：2017-12-29 13:07:48
【问题描述】：

我正在尝试模拟掷骰子 100 次，并打印我降落了多少 1/2/3/4/5/6 的结果。到目前为止，这是我的代码：我正在尝试使用 while 循环进行分配，并且我需要使用 (Math.random( )*6 + 1) 来生成数字。

public class RollingDice {

    public static void main(String args[]) {

        int count = 0; // number of times die was rolled
        int count1s = 0; // number of times 1 was rolled
        int count2s = 0; // number of times 2 was rolled
        int count3s = 0;
        int count4s = 0;
        int count5s = 0;
        int count6s = 0;

        while (count < 100) {
            count1s = (int) (Math.random( )*6 + 1);
            count2s = (int) (Math.random( )*6 + 1);
            count3s = (int) (Math.random( )*6 + 1);
            count4s = (int) (Math.random( )*6 + 1);
            count5s = (int) (Math.random( )*6 + 1);
            count6s = (int) (Math.random( )*6 + 1);

            count++;

    }
        System.out.println("Number of times the die was rolled: "+ count);
        System.out.println("Number of times 1 was rolled: " + count1s);
        System.out.println("Number of times 2 was rolled: " + count2s);
        System.out.println("Number of times 3 was rolled: " + count3s);
        System.out.println("Number of times 4 was rolled: " + count4s);
        System.out.println("Number of times 5 was rolled: " + count5s);
        System.out.println("Number of times 6 was rolled: " + count6s);

    }
}

我的代码当前打印：

Number of times the die was rolled: 100
Number of times 1 was rolled: 3
Number of times 2 was rolled: 1
Number of times 3 was rolled: 5
Number of times 4 was rolled: 2
Number of times 5 was rolled: 4
Number of times 6 was rolled: 4

如您所见，它滚动了 100 次，但它只保存了 1 次滚动的结果，而不是 100，我该如何解决这个问题？

【问题讨论】：

标签： java simulation dice

【解决方案1】：

在您的 while 循环的每次迭代中，您都在重新分配 count1s、count2s 和其他的值。相反，您应该做的是“掷骰子”，然后查看它的值，并增加适当的变量。

while (count < 100) {
    int diceRoll = (int) (Math.random() * 6 + 1);
    if (diceRoll == 1) 
        count1s++;
    else if (diceRoll == 2)
        count2s++;
    // ... you get the idea

    count++;
}

作为一个有趣的旁注，使用 Java 8 有一种更简单、更酷的方法来做到这一点。

        Stream.generate(() -> (int) (Math.random() * 6 + 1))
             .limit(100L)
             .collect(Collectors.groupingBy(num -> num, 
                 Collectors.counting()))
             .forEach((num, count) -> System.out.println("number of times " + num + " was rolled: " + count));

【讨论】：

非常感谢！！快把我逼疯了。很简单的人
Java 8 上不错的解决方案。谢谢。

【解决方案2】：

因为你的逻辑不正确。

在while 循环中，您为每个掷骰的出现时间分配了骰子的值。 => 每个计数器总是

此外，每次调用 Math.random() 都会给你新的价值 => 每次滚动都应该调用一次。

在这种情况下，使用switch - case 语句将是正确的。

  while (count < 100) {
        int num = (int) (Math.random( )*6 + 1);
        switch(num)  {
            case 1: 
                count1s++;
                break;
            case 2:
                count2s++;
                break;
            case 3: 
                count3s++;
                break;
            case 4: 
                count4s++;
                break;
            case 5:
                count5s++;
                break;
            case 6: 
                count6s++;
                break;
        }
        count++;
   }

【讨论】：

谢谢，忘了switch语句

【解决方案3】：

每次迭代你都在替换前一卷的数据。你可以将逻辑重写为

// initialization
while(count < 100){
   int currentRoll = (int) (Math.random() * 6 + 1);
   if(currentRoll == 1)
      count1s++;
  // Same logic for all occurances
}

【讨论】：