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Is it "safe" to have a ByteBuffer and a ByteArrayInputStream share an underlying byte [] as long they only read from it? If I read/get from one and then the other, since each has their own internal marks/counters etc., is there a possibility of a conflict?

user3416961
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Judging from the source of ByteBuffer.wrap and ByteArrayInputStream's constructor, it looks like both classes would store the array that you pass them without making a copy. It also appears that neither class would modify the array, making it safe to share the same byte[] array across multiple instances of ByteBuffer and ByteArrayInputStream.

Sergey Kalinichenko
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It is safe, with one caveat. There must be a happens before chain to ensure that the threads using the shared byte[] can see the last write to the byte[] prior to it becoming "effectively immutable".

In simple terms, the threads need to synchronize when setting up the sharing,

Stephen C
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  • OP didn't ask about multi-threading, but perhaps they should have. – markspace Mar 12 '17 at 14:28
  • Well ... to my mind ... "safe" includes all kinds of safety, including thread safety. As I read it, they are asking about thread safety, among other things. – Stephen C Mar 12 '17 at 14:30
  • The part of the code I'm using this in is sequential, but thanks for the heads up re: thread safety. I originally meant only in terms of somehow modifying the underlying `byte []` – user3416961 Mar 12 '17 at 14:34