Java built-in class that allows writing character files.
Java built-in class that prints formatted representations of objects to a text-output stream.
Printwriter is more effective than filewriter and filewriter is needed anyhow but this will work also if you want to do multiples people then just for-loop it and dont forget to close
Updating a double in a text file
I m not sure if printwriter or filewriter is better but printwriter worked for me
Writing textFields/textArea to text file