ByteBuffer's static "wrap" method -- managing memory

Question

Hello,
I have a function which will be called many, many times over:
     public static ByteBuffer byteArr2ByteBuff(byte[] data, int off, int len) {
          byte[] subData = new byte[len];
          try {
               System.arraycopy(data, off, subData, 0, len);
          } catch (Exception e) {
               e.printStackTrace();
          // TODO find out if null'ing out subData works? Curious if this helps efficiency? This function will get called a LOT...
          ByteBuffer out = ByteBuffer.wrap(subData);
          subData = null;
          return out;
My question this:
At the end of my code, I null out the "subData" array manually since I am not sure if the "wrap()" method will cause the subData to be held on, or get garbage collected.
Now, its not easy for me to test this out in my current system since I am actually using this on the Android platform (min API 8). Preferably, I would just "return ByteBuffer.wrap(subData);" and be done with it, but since this function will get calls 100's of thousands of times, I want to be doubly sure its efficent.

Answer 1

Thanks for the reply, let me give you some background information as to why the function will be called many times. I am creating an app on Android that works with Bluetooth and will accept streaming data. The data that is coming in is binary, so I need to cut the data into its chunks and feed it into a float, or short, or int, etc.
For example, after it comes out the "return ByteBuffer.wrap(..)" I take that output and do a .order(null).getFloat() on it, depending on the byte order.
As much as I wish I could have used JavaStruct (see GoogleCode) or the C/C++ style Structs to feed in data a-la #pragma(push), I don't see any other way to handle this kind of data. I am hoping that ByteBuffer is very memory efficient and fast.
Also, as for the "System.arraycopy()" usage, I could look into making that more efficient, however that would require all other methods calling byteArr2ByteBuff to modify how it sends data to this function.
Thanks for clearing the air on how Null doesn't have any effect though. If you have other ideas on how to handle the parsing of binary packets coming in through a socket, I am definitely all ears!
PS. I'd rather using Arrays.copyrange instead of the System.arraycopy method, but since I am making this app work for Android API8+, I am limited on the Arrays methods.
Edited by: 1000047 on Apr 17, 2013 11:42 PM
For example, here is an example of the usage (sorry not sure how to properly format in sans-serif on this forum yet!)
          public void unpack(byte[] data) {
               int i = -fSize; //fSize == 4
               accx = Streams.byteArr2ByteBuff(data, i += fSize, fSize).order(null).getFloat();
               accy = Streams.byteArr2ByteBuff(data, i += fSize, fSize).order(null).getFloat();
               accz = Streams.byteArr2ByteBuff(data, i += fSize, fSize).order(null).getFloat();
               gyrox = Streams.byteArr2ByteBuff(data, i += fSize, fSize).order(null).getFloat();
               gyroy = Streams.byteArr2ByteBuff(data, i += fSize, fSize).order(null).getFloat();
               gyroz = Streams.byteArr2ByteBuff(data, i += fSize, fSize).order(null).getFloat();
               temp = Streams.byteArr2ByteBuff(data, i += fSize, fSize).order(null).getFloat();
Edited by: 1000047 on Apr 17, 2013 11:45 PM