title: Sending messages to a swing JTextArea from different places
body: <p>I have a JTextArea always visible in my main app window (a Log if you like), and I want to use it to display activity going on in the system (like mock-debug output you'd do with System.out.println() in if conditions or whatever) </p>
  
  <p>I mean high level things the user does, (like "successfully loaded file " or " written to disk", " completed" etc)</p>
  
  <p>Thing is such messages can be generated anywhere in my system mainly in another package the classes of which deal with the data and computation, and they're unaware of the GUI.</p>
  
  <p>Maybe save the messages to a temp file and the textarea "monitors" that file for changes, how can this be done?</p>