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Thread: Program of creating and printing a random phone number that takes only 8-9 in first three digits

  1. #1
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    Default Program of creating and printing a random phone number that takes only 8-9 in first three digits

    I am going through a Lewis and Loftus book doing all of the examples, trying to get myself reacquainted with the Java language. I've included the exercise's requirements inside of the [CODE] tags.

    I've tried everything from a BUNCH of if statements, to trying to make up the 'area' variable out of three separate characters, but I cannot seem to get it right. How do I go about limiting the output so that there are no 8 or 9s?

    import java.util.Random;
     
    /* Write an application that creates and prints a random phone number
    of the form XXX-XXX-XXXX. Include the dashes in the output. Do not
    let the first three digits contain an 8 or 9 (but donít be more restrictive
    than that), and make sure that the second set of three digits is
    not greater than 742.*/
     
    class Test {
     
      public static void phoneNumber(){
        Random random = new Random();
     
        int area = random.nextInt(900)+100;
        int mid = random.nextInt(643)+100;
        int last = random.nextInt(9000)+1000;
     
        System.out.println(area+"-"+mid+"-"+last);
      }
     
      public static void main(String[] args){
        phoneNumber();
     
       }
      }
    Last edited by Deep_4; November 8th, 2012 at 01:14 PM.


  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: Formatting Output

    I used strings to hold the values, since number data types don't keep track of the zeros very well.
        public static void main (String[] args)
        {
            Random gen = new Random();
            // first 3 digits. Can't contain an 8 or 9
            String areaCode = "";
            for (int i = 0; i < 3; i++)
            {
                areaCode += gen.nextInt(8);
            }
            // second three digits must be less than or equal to 742
            String second = "" + gen.nextInt(743);
            while (second.length() < 3)
            {
                second = "0" + second;
            }
            // last 4 can be anything
            String last = "" + gen.nextInt(10000);
            while (last.length() < 4)
            {
                last = "0" + last;
            }
            System.out.printf(areaCode + "-" + second + "-" + last);
        }

  3. The Following User Says Thank You to helloworld922 For This Useful Post:

    cfmonster (August 19th, 2009)

  4. #3
    Super Moderator Json's Avatar
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    Default Re: Formatting Output

    Yeah I agree with helloworld, after the experience I got from the telecom industry I noticed that integers is the worst way of representing phone numbers.

    // Json

  5. #4
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    Default Re: Formatting Output

    Thanks. Slowly but surely getting the hang of Java again

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