you have in your code this:
System.out.println(name +"\t" + "-"+ phonenumber);
and this:
pw.println( name + "\t" + phonenumber);
and this:
recordTextArea.setText(phonenumber);
it seems you know how to access the textArea (unless this is not your code),
so just refer to the JTextArea apidocs for a method to add, or append (hint), text.