Convert a UUID to an unsigned BigInteger #java #UUID #BigInteger

convertUuidToBigInteger.java

    public static final BigInteger B = BigInteger.ONE.shiftLeft(64); // 2^64
    public static final BigInteger L = BigInteger.valueOf(Long.MAX_VALUE);

    public static BigInteger convertToBigInteger(UUID id)
    {
        BigInteger lo = BigInteger.valueOf(id.getLeastSignificantBits());
        BigInteger hi = BigInteger.valueOf(id.getMostSignificantBits());
        
        // If any of lo/hi parts is negative interpret as unsigned
        
        if (hi.signum() < 0) 
            hi = hi.add(B);
      
        if (lo.signum() < 0) 
            lo = lo.add(B);
        
        return lo.add(hi.multiply(B));
    }

    public static UUID convertFromBigInteger(BigInteger x)
    {
        BigInteger[] parts = x.divideAndRemainder(B);
        BigInteger hi = parts[0];
        BigInteger lo = parts[1];
        
        if (L.compareTo(lo) < 0)
            lo = lo.subtract(B);
        
        if (L.compareTo(hi) < 0)
            hi = hi.subtract(B);
        
        return new UUID(hi.longValueExact(), lo.longValueExact());
    }

And one string based option for converting back:

    public static UUID convertFromBigInteger(BigInteger bigInteger) {
        String bigIntegerAsHex = bigInteger.toString(16);
        String leftPadded = org.apache.commons.lang3.StringUtils.leftPad(bigIntegerAsHex, 32, "0");
        String withDashes = leftPadded.replaceAll("^(.{8})(.{4})(.{4})(.{4})(.{12})$", "$1-$2-$3-$4-$5");
        return UUID.fromString(withDashes);
    }