Is there a way to determine if an inputstream is readOnly?

Question

I was thinking something like a

File file =new File(inputStream) // not possible though. file.canWrite,

but i cant seem to find a solution to conv

Answer 1

You seem to have it backwards.

By definition, an InputStream will only ever allow you to read a stream of bytes, wherever that stream of bytes comes from. It may be from a file, or a network socket, or a custom provider. By its very definition, you can only read from an InputStream anyway.

Since you seem to be working with files here, you can check whether a file is read only for the user running the current process using:

final Path path = Paths.get("path/to/my/file");

// is it writable? If no, consider "read only"
final boolean canWrite = Files.isWritable(path);

And to open an InputStream from a Path, use:

try (
    final InputStream in = Files.newInputStream(path);
) {
    // work with "in"
}