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  1. Commons Math
  2. MATH-153

RandomDataImpl nextInt(int, int) nextLong(long, long)

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Critical
    • Resolution: Fixed
    • Affects Version/s: 1.1
    • Fix Version/s: 1.2
    • Labels:
      None

      Description

      RandomDataImpl.nextInt(Integer.MIN_VALUE, Integer.MAX_VALUE) suffers from overflow errors.

      change
      return lower + (int) (rand.nextDouble() * (upper - lower + 1));
      to
      return (int) (lower + (long) (rand.nextDouble()*((long) upper - lower + 1)));

      additional checks must be made for the nextlong(long, long) method.
      At first I thought about using MathUtils.subAndCheck(long, long) but there is only an int version avalible, and the problem is that subAndCheck internaly uses long values to check for overflow just as my previous channge proposes. The only thing I can think of is using a BigInteger to check for the number of bits required to express the difference.

        Attachments

        1. Test.diff
          3 kB
          Remi Arntzen
        2. diff.txt
          0.9 kB
          Remi Arntzen

          Activity

            People

            • Assignee:
              Unassigned
              Reporter:
              remi_arntzen Remi Arntzen
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              Dates

              • Created:
                Updated:
                Resolved: