Unique 10-digits Sequential Number in Java

 private static Long UniqueRandomInteger() {

        int Start = 1000000000;
        long End = 9999999999L;

        Random random = new Random();

if (Start > End) {
            throw new IllegalArgumentException("Start cannot exceed End.");
        }
        //get the range, casting to long to avoid overflow problems
        long range = aEnd - (long) aStart + 1;
        //  System.out.println("range>>>>>>>>>>>"+range);

        // compute a fraction of the range, 0 <= frac < range
        long fraction = (long) (range * aRandom.nextDouble());
        //   System.out.println("Fraction>>>>>>>>>>>"+fraction);

         randomNumber = fraction + (long) aStart;
         System.out.println("randomNmber>>>>>>>>>>>" + randomNumber);

         return randomNumber;
    }

  Format - 2 :

 long number = (long) Math.floor(Math.random() * 9000000000L) + 1000000000L;