byte[] to file in Java

Use Apache Commons IO

FileUtils.writeByteArrayToFile(new File("pathname"), myByteArray)

Or, if you insist on making work for yourself…

try (FileOutputStream fos = new FileOutputStream("pathname")) {
   fos.write(myByteArray);
   //fos.close(); There is no more need for this line since you had created the instance of "fos" inside the try. And this will automatically close the OutputStream
}