UUID myuuid = UUID.randomUUID();
long highbits = myuuid.getMostSignificantBits();
long lowbits = myuuid.getLeastSignificantBits();
System.out.println("My UUID is: " + highbits + " " + lowbits);

long hi = id.getMostSignificantBits();
long lo = id.getLeastSignificantBits();
byte[] bytes = ByteBuffer.allocate(16).putLong(hi).putLong(lo).array();
BigInteger big = new BigInteger(bytes);
String numericUuid = big.toString().replace('-','1'); // just in case

final int[] pattern = { 8, 4, 4, 4, 12 };

final int[] versionBit = { 2, 0 }; /* 3rd group, first bit */
final int version = 4;

final int[] reservedBit = { 3, 0 }; /* 4rd group, first bit */
final int reserved = 8; /* 8, 9, A, or B */

Random rand = new Random();

String numericUuid = "";

for (int i = 0; i < pattern.length; i++) {
    for (int j = 0; j < pattern[i]; j++) {
        if (i == versionBit[0] && j == versionBit[1])
            numericUuid += version;
        else if (i == reservedBit[0] && j == reservedBit[1])
            numericUuid += reserved;
        else
            numericUuid += rand.nextInt(10);
    }

    numericUuid += "-";
}

UUID uuid = UUID.fromString(numericUuid.substring(0, numericUuid.length() - 1));
System.out.println(uuid);

UUID uuid = UUID.randomUUID();

while (StringUtils.containsAny(uuid.toString(), new char[] { 'a', 'b', 'c', 'd', 'e', 'f' })) {
    uuid = UUID.randomUUID();
}

System.out.println(uuid);