If you are using the recommended text check out the "The Length of an Entire Arry Versus a String in an Array" topic on page 111. If I understand your question I think that will shed some light on the issue. If you're like me you probably started out with using a specific index on the array and if you don't pass a parameter you'll get an array index out of bounds exception.
I've not submitted 1b (waiting on nitpicks for 1a) but the stuff I cited above proved very useful. If you don't have the text check out the API for
Java. The Array class has a data field called length.
Good luck.