How to read parts of binary file again if DataInputStream does not support mark/reset?

It is not DataInputStream that doesn't support mark/reset. DataInputStream simply delegates the calls to mark/reset to the underlying stream (in this case a FileInputStream). The FileInputStream does however not support mark/reset operations (iirc).

The solution to this problem is to first wrap the FileInputStream in a BufferedInputStream before passing it to the DataInputStream. That should make it possible to use the desired operations. Ie.

Wrap in a BufferedInputStream it implements mark.

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