Converting a java byte array to a String

As jtahlborn pointed out, there is nothing special about NUL (char = 0) in Java strings - it's just another character. Because of this, the (or, at least one) solution is to remove the extra characters when converting the source data it into a Java string.

To do that, use the String constructor overload that takes in an array offset/length and a charset:

byte[] byteArr = new byte[128];
myFill(byteArr);
String myString = new String(byteArr, 0, encodedStringLength, "US-ASCII");

Then it's just a matter of finding out the "encodedStringLength" which might look like so (after filling byteArr, of course):

int encodedStringLength = Arrays.asList(byteArr).indexOf(0);

That's not the "most efficient" way, sure, but it ought to do the trick. Keep in mind that indexOf could return -1 if the source string uses all 128 bytes (e.g. is not NUL terminated).

Also, one should generally (or, perhaps, always) specify a character encoding with String-from-byte[] constructors as the "default encoding" can vary across run-time environments. For instance, if the default encoding was UTF-16 then the original code would also have severely mangled the ASCII source data.

Alternatively, if one didn't care about leading/trailing spaces or control characters then the following would also work (once again, note the explicit character encoding):

String myString = new String(byteArr, "US-ASCII").trim();

This is because trim removes all leading/trailing characters with values less than or equal to 0x20 (Space) - including NUL characters.