Java needs an immutable byte array wrapper

John Rose john.r.rose at
Sat Nov 12 18:04:56 UTC 2016

On Nov 12, 2016, at 8:45 AM, Keith Turner <keith at> wrote:
> While trying to design an API for Fluo, its become clear to me that
> Java could really benefit from an immutable byte array wrapper.
> Something like java.lang.String except for byte arrays instead of char
> arrays.  It would be nice if this new type interoperated well with
> byte[], String, ByteBuffer, InputStream, OutputStream etc.
> I wrote the following blog post about my experiences with this issue
> while designing an API for Fluo.
> <>

That's a good blog entry; thanks, especially the pointer to ByteString.

Of course Java needs a type like that, but our story for immutability
is still in flux, so folks are being cautious about adopting such features.

In a similar vein, I would like to see the ability to freeze Java arrays
(make them immutable), and (independently) add more API points
to them.  But the ideas are not fully baked yet.

See also this application for immutable bytes: <>

— John

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