SecureRandom hash

I am trying to see if I can get a proper distribution based on secure random hash. I always seem to get double for my first index. Is there something wrong that I am doing

    SecureRandom sr = new SecureRandom();

    sr.setSeed(sr.generateSeed(16));
    int zero = 0;
    int one = 0;
    int two = 0;
    int three = 0;
    int four = 0;
    int five = 0;
    int six =0;


    for (int i = 0 ; i < 100000; i++) {
        long index = sr.nextLong()%6;
        if(index == 0)
            zero++;
        else if (index == 1)
            one++;
        else if(index == 2)
            two++;
        else if(index == 3)
            three++;
        else if(index == 4)
            four++;
        else if(index == 5)
            five++;
    }
    System.out.println(zero);
    System.out.println(one);
    System.out.println(two);
    System.out.println(three);
    System.out.println(four);
    System.out.println(five);
    System.out.println(six);

Take a look at the first line of the output

Here is the output
16548
8362
8314
8175
8272
8210

Solution

You're ignoring the fact that SecureRandom.nextLong() can return negatives. So your code is only catching half of all non-zero indexes because -7 % 6 == -1, but it's catching all zero indexes because -6 % 6 == 0.

If you want all values to land between 0 and 5, just use Math.abs():

long index = Math.abs(sr.nextLong()%6);

Sample output: