如何使方法打印出特定数字的滚动次数？

Question

i have to make a dice program. the program asks how many times you want to roll the dice, and then it asks what number you want the statistics for (2-12). it then rolls the dice (x) amount of times and gives you the number rolled each time. then it'll tell you the amount of times each number (2-12) was rolled, and it's supposed to finish with the program telling you what the percentage of the number you asked to see statistics for (example: of the 25 dice rolls, 2 rolls added to a total of 10. the percentage of 10s rolled is 8%).

i have to use methods for this program, and my statistics method prints 1 instead of however many times 7 shows up (i'm using 7 as a sort of tester for what i'm doing since 7 is supposed to pop up a lot during dice rolls).

i'm using drjava and i'm not supposed to be using a debugger for my programs since our instructor hasn't taught us how to do it yet! i think my loop is the problem because i'm trying to get d to print.

also, how would i find the percentage of times that my selected number was rolled?

import java.util.*; 
public class EZD_diceRoll
 {
  public static void main(String args[])
{



  EZD_diceRoll.roll();
  EZD_diceRoll.statistics(d);
}

 private static int die1;
 private static int die2;
 private static int total;
 public static int number;
 public static int d;
 public static int times;

 public static void roll()
 {
  Random nums = new Random();
  Scanner kbReader = new Scanner(System.in);

  System.out.print("How many times would you like to roll?");
  times = kbReader.nextInt();
  System.out.print("What number (dice roll total) do you want the statistics 
  for (2 - 12)?");
  number = kbReader.nextInt();


  for(int a = 1; a < times + 1; a++)
 {
  die1 = 1 + nums.nextInt(6);
  die2 = 1 + nums.nextInt(6);
  total = die1 + die2;

  System.out.println("Dice roll #" + a + " is " + total);
 }
}


public static void statistics(int d)
{

  for(int c = 0; c < times + 1; c++)
    {

    if(total == 7)
      {
        d++;
      }
    }
  System.out.println("The number of 7's thrown was " + d);
 }
}

Answer 1

Use a java.util.HashMap ,

HashMap<Integer, Integer> map = new HashMap<>();

The key represents the specific number, the value represents the frequecy. When you get a number, check if it exists in the map. If not, put it into the map with initial frequency 1 . Otherwise, increment the requency.

Answer 2

initialize counters(int var) for dice output values(2-12) and use switch statement inside for loop ,for each roll output give a case inside switch and increment counter for each case and these counter values give number of times the value is rolled.

the below code prints for each roll if u want only final number just use all system.out.print statements outside(after) for loop instead of using them in case statement.

  int[] count=new int[10] //counter for values 2-12


for(int a = 0; a < times + 1; a++)      
{
  die1 = 1 + num.nextInt(6);

  die2 = 1 + num.nextInt(6);

  total = die1 + die2;

switch(total)

  {     
 case 2:
 count[0]++;

 System.out. print("dice 2 rolled" +count[0] +" time");
 break;


 case 3:

 count[1]++;

 System.out. print("dice 3 rolled" +count[1] +" time");
 break;


  case 4:

  count[2]++;

  System.out. print("dice 4 rolled" +count[2] +" time");
 break;

.

.

 .

 .

case 12:

 count[10]++;

System.out. print("dice 12 rolled" +count[10] +" time");
break;

} }