Trefex Blog

Hi,

So you have been driving yourself crazy looking over the Internet on how to do those bloody conversions from a

double

to a

byte[]

array using << or <<< and god knows what else in Java?

Well you have come to the right place.

This function takes a double as argument and converts it to an 8-Byte array in Big Endian format. Alternatively, you can use the Little Endian format by uncommenting the 2nd line. For more information on Endianess you can check http://en.wikipedia.org/wiki/Endianness

public static byte[] doubleToByteArray(double valToConv) {
  ByteBuffer bb = ByteBuffer.allocate(8);
  //bb.order(ByteOrder.LITTLE_ENDIAN);
  bb.putDouble(valToConv);
  bb.flip();
  byte[] bbb= new byte[8];
  bb.get(bbb, 0, 8);
  return bbb;
}

This method takes an 8-Byte Array in Big Endian and transforms it back to a Double.

public static double byteArrayToDouble(byte[] arrayToConv) {
  ByteBuffer bb = ByteBuffer.allocate(byteArrayToConv.length);
  //bb.order(ByteOrder.LITTLE_ENDIAN);
  bb.put(byteArrayToConv);
  bb.flip();
  return bb.getDouble();
}

As a final note, if you look at the Java API you will find many more methods in the ByteBuffer Class to handle conversions to Byte Arrays, like from Int, Long, etc...

Enjoy,