Writing byte array to an UTF8-encoded file

Question

Given a byte array in UTF-8 encoding (as result of base64 decoding of a String) - what is please a correct way to write it to a file in UTF-8 encoding?

Is the following source code (writing the array byte by byte) correct?

OutputStreamWriter osw = new OutputStreamWriter(
    new FileOutputStream(tmpFile), Charset.forName("UTF-8"));
for (byte b: buffer)
    osw.write(b);
osw.close();

Solution

Don't use a Writer. Just use the OutputStream. A complete solution using try-with-resource looks as follows:

try (FileOutputStream fos = new FileOutputStream(tmpFile)) {
    fos.write(buffer);
}

Or even better, as Jon points out below:

Files.write(Paths.get(tmpFile), buffer);

Comments

[Jon Skeet]

Or Files.write to make it even simpler.

[Alexander Farber]

When I use just OutputStream I get the error (later, when trying to use Efficient XML): Invalid byte 1 of 1-byte UTF-8 sequence. So I am trying to find a proper way to write the byte array to file in UTF-8 encoding

[aioobe]

But you said the array is in UTF-8 encoding, no? I think you should check your assumptions. Make sure the buffer is indeed proper UTF-8 and that it represents something Efficient XML can handle.

[Nitin Dandriyal]

I think the problem is while reading in that case, create a buffer read and write simultaneously