循環中的隨機數和計數發生

Question

我對Java很陌生，目前有一個處理循環和隨機數的任務。問題如下：修改ThrowingPairsOfDice.java進行計數，並將這對數相加爲2，總和爲3，總和爲4，總和爲5，總和爲6.顯示結果。

這是需要修改的代碼：

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

public class ThrowingPairsOfDice 
{ 

/** 
* main method simulates throwing 2 dice 1,000,000 times 
* 
*/ 
    public static void main(String[] args) 
    { 
     Random die1 = new Random(); 
     Random die2 = new Random(); 
     int throwOfDice=0; 

     System.out.println("How many times should I throw two dice?"); 
     Scanner kb = new Scanner(System.in); 

     int numberOfTimes = kb.nextInt(); 

     // throw the dice the number of times requested 

     for (int i=1;i<=numberOfTimes;i++) 
     { 
      int toss1 =die1.nextInt(5)+1; 
      int toss2 =die2.nextInt(5)+1; 
      throwOfDice = toss1 + toss2; 
      System.out.println(toss1+ "+" +toss2+ "= " +throwOfDice); 
     } 

    } 
} 

我不知道如何修改這個程序來計算時代的一對骰子將總結爲給定值的數量，從而幫助將不勝感激！謝謝。

Answer 1

你只新Random實例來生成兩個隨機int值，你可以使用printf()得到格式化輸出和if和else if總結你的骰子。類似的，

Random die = new Random(); // <-- only need one. 
// The number of sides to the die. 
int sides = 6; 
// Variables to count the results 
int rolled2 = 0; 
int rolled3 = 0; 
int rolled4 = 0; 
int rolled5 = 0; 
int rolled6 = 0; 

// throw the dice the number of times requested 
for (int i = 1; i <= numberOfTimes; i++) { 
    int toss1 = 1 + die.nextInt(sides); 
    int toss2 = 1 + die.nextInt(sides); 
    int throwOfDice = toss1 + toss2; 
    System.out.printf("%d + %d = %d%n", toss1, toss2, throwOfDice); 
    if (throwOfDice == 2) { 
     rolled2++; 
    } else if (throwOfDice == 3) { 
     rolled3++; 
    } else if (throwOfDice == 4) { 
     rolled4++; 
    } else if (throwOfDice == 5) { 
     rolled5++; 
    } else if (throwOfDice == 6) { 
     rolled6++; 
    } 
} 
System.out.printf("2 = %d, 3 = %d, 4 = %d, 5 = %d, 6 = %d%n", rolled2, 
     rolled3, rolled4, rolled5, rolled6); 

Answer 2

您需要使用額外的變量來存儲＃總數。在我的答案中，我使用數組sum []並使用die減去兩個之和來引用它。

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

public class ThrowingPairsOfDice 
{ 

/** 
* main method simulates throwing 2 dice 1,000,000 times 
* 
*/ 
    public static void main(String[] args) 
    { 
     Random die1 = new Random(); 
     Random die2 = new Random(); 
     int throwOfDice=0; 
     int [] sum = {0, 0, 0, 0, 0}; 


     System.out.println("How many times should I throw two dice?"); 
     Scanner kb = new Scanner(System.in); 

     int numberOfTimes = kb.nextInt(); 

     // throw the dice the number of times requested 

     for (int i=1;i<=numberOfTimes;i++) 
     { 
      int toss1 =die1.nextInt(5)+1; 
      int toss2 =die2.nextInt(5)+1; 
      throwOfDice = toss1 + toss2; 
      System.out.println(toss1+ "+" +toss2+ "= " +throwOfDice); 
      if (throwOfDice < 7) sum[throwOfDice - 2]++; 
     } 

     for (int i=0;i<=4;i++) 
     { 
      System.out.println("# of throws totalling " + (i + 2) + " = " + sum[i]); 
     } 
    } 
}