How write big endian ByteBuffer to little endian in Java

Question

I currently have a Java ByteBuffer that already has the data in Big Endian format. I then want to write to a binary file as Little Endian.

Here's the code which just writes the file still in Big Endian:

 public void writeBinFile(String fileName, boolean append) throws FileNotFoundException, IOException
 {
     FileOutputStream outStream = null;
     try
     {
         outStream = new FileOutputStream(fileName, append);
         FileChannel out = outStream.getChannel();
         byteBuff.position(byteBuff.capacity());
         byteBuff.flip();
         byteBuff.order(ByteOrder.LITTLE_ENDIAN);
         out.write(byteBuff);
     }
     finally
     {
         if (outStream != null)
         {
            outStream.close();
         }
     }

 }

Note that byteBuff is a ByteBuffer that has been filled in Big Endian format.

My last resort is a brute force method of creating another buffer and setting that ByteBuffer to little endian and then reading the "getInt" values from the original (big endian) buffer, and "setInt" the value to the little endian buffer. I'd imagine there is a better way...

Answer 1

Endianess has no meaning for a byte[]. Endianess only matter for multi-byte data types like short, int, long, float, or double. The right time to get the endianess right is when you are writing the raw data to the bytes and reading the actual format.

If you have a byte[] given to you, you must decode the original data types and re-encode them with the different endianness. I am sure you will agree this is a) not easy to do or ideal b) cannot be done automagically.