I'm not sure I get what that codes supposed to achieve?
For example:
You read a line from the file, then split on a new line.
But there shouldn't be any new lines in that line as you've just read in a line.
Next is this:
The join() method takes a separator and either a load of CharSequences, or a collection of CharSequences.
In your case you supply only one
String, so there's nothing to actually join.
Taking those two bits into account, I would take a step back and figure out what your steps should be and what should be the output from each step.
Start with reading from the file.
What are you reading and what do you want to do with each line you read?