Java - Converting Hex string to double

Question

Im attempting to decode the value of "Well-known Binary" format in Java. The following Node script does what I need

Buffer.from('A4C0A7DEBFC657C0', 'hex').readDoubleLE() // returns -95.1054608

My question is, what is the equivalent Java code? Nothing I have tried has given the same result.

See: https://en.wikipedia.org/wiki/Well-known_text_representation_of_geometry

I am running this as part of an ingest pipeline in OpenSearch, so I can't use 3rd party libraries.

Answer 1

I landed on a solution that doesn't require ByteBuffer as it's not available in painless.

// convert hex string to byte array
int l = hex.length();    
byte[] data = new byte[l / 2];    
for (int i = 0; i < l; i+= 2) {        
  data[i / 2] = (byte) ((Character.digit(hex.charAt(i), 16) << 4)              
    + Character.digit(hex.charAt(i + 1), 16));        
}

// convert byte array to double
long bits = 0L;
for (int i = 0; i < 8; i++) {
  bits |= (data[i] & 0xFFL) << (8 * i);
}
return Double.longBitsToDouble(bits);