Java Programming

I have a problem with a parsing system I'm trying to implement for my app. It involves passing an InputStream that hasn't been finished being read into another method, kinda something like this:

public void load( InputStream stream ) {
  BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
  try {
    // ... read a few first lines of the stream, until
    aSubDataType.load(stream);  // I try to pass the unfinished stream to be read by another object
    // finish read the rest of the stream for this data type
  } catch (IOException e) { ... }
}

but everytime the stream is passed into the secondary method, any String read from it is null >.< resulting in inexplicable NullPointerException everywhere.

Any ideas? ;-)