title: Communication between already existing classes
body: <p>I am sorry if this question seems pretty basic and there is already an answer for that, but unless I make it into a proper question, google won't find it.</p>
  
  <p>I have a main class that is a JFrame(there is and will be only one object, let's call it "main"), it creates and calls another JFrame class(let's call it window2), however, I still need this window2 to call methods from the already existing main class. Normally window2 would have something like     Main mainMenu = new Main();.
  But this obviously creates a new object of main, I still want to refer to the already existing object and get information from it.</p>