How can I read a file to an InputStream then write it into an OutputStream in Scala?

Question

I'm trying to use basic Java code in Scala to read from a file and write to an OutputStream, but when I use the usual while( != -1 ) in Scala gives me a warning "comparing types of Unit and Int with != will always yield true".

The code is as follows:

    val file = this.cache.get(imageFileEntry).getValue().asInstanceOf[File]     response.setContentType( "image/%s".format( imageDescription.getFormat() ) )      val input = new BufferedInputStream( new FileInputStream( file ) )     val output = response.getOutputStream()      var read : Int = -1      while ( ( read = input.read ) != -1 ) {         output.write( read )     }      input.close()     output.flush() 

How am I supposed to write from an input stream to an output stream in Scala?

I'm mostly interested in a Scala-like solution.

Answer 1

You could do this:

Iterator  .continually (input.read) .takeWhile (-1 !=) .foreach (output.write) 

Answer 2

If this is slow:

Iterator  .continually (input.read) .takeWhile (-1 !=) .foreach (output.write) 

you can expand it:

val bytes = new Array[Byte](1024) //1024 bytes - Buffer size Iterator .continually (input.read(bytes)) .takeWhile (-1 !=) .foreach (read=>output.write(bytes,0,read)) output.close()