How can I write a byte array to a file in Java?

Question

How to write a byte array to a file in Java?

Answer 1

         File file = ...
         byte[] data = ...
         try{
            FileOutputStream fos = FileOutputStream(file);
            fos.write(data);
            fos.flush();
            fos.close();
         }catch(Exception e){
          }

but if the bytes array length is more than 1024 you should use loop to write the data.

Answer 2

A commenter asked "why use a third-party library for this?" The answer is that it's way too much of a pain to do it yourself. Here's an example of how to properly do the inverse operation of reading a byte array from a file (sorry, this is just the code I had readily available, and it's not like I want the asker to actually paste and use this code anyway):

public static byte[] toByteArray(File file) throws IOException { 
   ByteArrayOutputStream out = new ByteArrayOutputStream(); 
   boolean threw = true; 
   InputStream in = new FileInputStream(file); 
   try { 
     byte[] buf = new byte[BUF_SIZE]; 
     long total = 0; 
     while (true) { 
       int r = in.read(buf); 
       if (r == -1) {
         break; 
       }
       out.write(buf, 0, r); 
     } 
     threw = false; 
   } finally { 
     try { 
       in.close(); 
     } catch (IOException e) { 
       if (threw) { 
         log.warn("IOException thrown while closing", e); 
       } else {
         throw e;
       } 
     } 
   } 
   return out.toByteArray(); 
 }

Everyone ought to be thoroughly appalled by what a pain that is.

Use Good Libraries. I, unsurprisingly, recommend Guava's Files.write(byte[], File).