IndexOutOfBounds Exception

Question

I'm trying a small program that would read a file, convert that to a array of bytes and zip the bytes and return the zipped bytes back as an array. However, I'm getting IndexOutOfBounds thrown. Here is what I have so far tried!

private def getBytePayload(): Array[Byte] = {
  val inputJson: String = Source.fromURL(getClass.getResource("/small_json.txt")).mkString

  val bin: ByteArrayInputStream = new ByteArrayInputStream(inputJson.getBytes())
  val bos: ByteArrayOutputStream = new ByteArrayOutputStream()

  println("The unCompressed stream size is = " + inputJson.size) // Prints 5330

  val gzip: GZIPOutputStream = new GZIPOutputStream(bos)

  val buff = new Array[Byte](1024)

  var len = 0
  while((len = bin.read(buff)) != -1) {
    gzip.write(buff, 0, len) // java.lang.IndexOutOfBoundsException is thrown!
  }

  println("The compressed stream size is = " + bos.toByteArray.size)

  bos.toByteArray
}

Any pointers as to what has gone wrong?

Answer 1

As far as what the problem is, I'm not exactly sure. However, the following code should be revealing. See what it it tells you:

val buff = new Array[Byte](1024)

var len = 0
while((len = bin.read(buff)) != -1) {

   //Print out actual contents of buff:

   for(int i = 0; i < buff.length; i++)  {
      System.out.print(i + "=" + buff[i] + ", ");
   }
   System.out.println();

   gzip.write(buff, 0, len) // java.lang.IndexOutOfBoundsException is thrown!
}

This is just my style-opinion, but I personally find this confusing

while((len = bin.read(buff)) != -1) {

and would change it to

len = bin.read(buff);
while(len != -1)  {

   //do stuff

   len = bin.read(buff);
}