Java: Need to create PDF from byte-Array

One can utilize the autoclosable interface that was introduced in java 7.

try (OutputStream out = new FileOutputStream("out.pdf")) {
   out.write(bArray);
}

Sending your output through a FileWriter is corrupting it because the data is bytes, and FileWriters are for writing characters. All you need is:

OutputStream out = new FileOutputStream("out.pdf");
out.write(bArray);
out.close();