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Apprentice
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posted by  CollegeMath on 11/3/2009 5:04:25 PM  |  status: Closed  |  Earned Karma: 134

Java, Dice Tossing

Course Textbook Chapter Problem Needs by
Software Design N/A N/A N/A 11/3/2009 at 10:00:00 PM
Question Details:

I want to write a program that would do this in java. 

Simulate tossing a dice 1000 times.

Keep count of how often each integer gets roled.

List the resulting frequency for each integer as a count and as percentage. 
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Oracle
Karma Points: 18,830
posted by Marth on 11/3/2009 6:39:12 PM  |  status: Live
Asker's Rating: Helpful   
Response Details:
Let us first write a method that rolls a die once.

 public static int rollDie()
{
      return (int)(Math.random()*6+1);
}



public static void main(String[] args)
{
      // create an array to store the number of times each integer is rolled
     
      // for simplicity, I will use array size 7, with [1 - 6] as the possible outputs
     
      int[] output = new int[7];
     
      // roll die 1000 times
      for(int x = 0; x < 1000; x++)
      {
            output[rollDie()]++;
      }

      // print results
      for(int i = 1; i<=6; i++)
      {
            // print count and percentage
            System.out.println(i+": "+output[i]+" rolls; "+String.format("%.1f", (output[i]/10.0))+"%");
      }
}


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Java Genius

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Apprentice
Karma Points: 134
posted by CollegeMath on 11/3/2009 7:42:29 PM  |  status: Live
Asker's Rating: N/A-Posted by Person Asking Question   
Response Details:

I get this error messsage when running it. «Ï 


----jGRASP exec: java RollingDice
ÏϧÏException in thread "main" java.util.IllegalFormatConversionException: f != java.lang.Integer
ÏϧϠ       at java.util.Formatter$FormatSpecifier.failConversion(Formatter.java:3999)
ÏϧϠ       at java.util.Formatter$FormatSpecifier.printFloat(Formatter.java:2722)
ÏϧϠ       at java.util.Formatter$FormatSpecifier.print(Formatter.java:2667)
ÏϧϠ       at java.util.Formatter.format(Formatter.java:2433)
ÏϧϠ       at java.util.Formatter.format(Formatter.java:2367)
ÏϧϠ       at java.lang.String.format(String.java:2769)
ÏϧϠ       at RollingDice.main(RollingDice.java:19)
ÏϧÏ
ÏÏ§Ï ----jGRASP wedge: exit code for process is 1.
ÏÏ©Ï ----jGRASP: operation complete.
¼¼ÏÏ
Oracle
Karma Points: 31,937
posted by rapunzel on 11/3/2009 8:07:10 PM  |  status: Live
Asker's Rating: Lifesaver   
Response Details:
please rate - thanks

worked fine for me.

I just moved the method after the main.  Used jGrasp, which I think you used. 
This is my output

 ----jGRASP exec: java untitled2

1: 176 rolls; 17.6%
2: 166 rolls; 16.6%
3: 153 rolls; 15.3%
4: 149 rolls; 14.9%
5: 190 rolls; 19.0%
6: 166 rolls; 16.6%

 ----jGRASP: operation complete





public class untitled2
{
public static void main(String[] args)
{
      // create an array to store the number of times each integer is rolled
     
      // for simplicity, I will use array size 7, with [1 - 6] as the possible outputs
     
      int[] output = new int[7];
     
      // roll die 1000 times
      for(int x = 0; x < 1000; x++)
      {
            output[rollDie()]++;
      }

      // print results
      for(int i = 1; i<=6; i++)
      {
            // print count and percentage
            System.out.println(i+": "+output[i]+" rolls; "+String.format("%.1f", (output[i]/10.0))+"%");
      }
}

public static int rollDie()
{
      return (int)(Math.random()*6+1);
}

}
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