situation_handwritten.java

    /**
     The task:
      - FX-Windows is running (main stage)
      - User should enter a new password in a stage (pw stage)
      - after entering the password, the main stage should go on

     The Problem:
      - main stage does not wait, goes on before password is entered

     The solutions:
      - two like as following

     Problem:
      - Solution 1 needs much modifications in the code
      - Solution 2 does not work for JavaFX (Thread is no FX-Thread)

     Question:
      - easy solution for FX?


      SEE IMPLEMENTATION at "simpleDemo" folder, but no FX
    */


    /**
        ONLY PSEUDO CODE !!!
    */

    public static char[] getPassword(String message) {
        run = true;
        showWindow(message);   // JFrame or FX-Window

        // while (run);  // infinite loop, gui hangs, so no solution
        run = false;

        // Working on the insert data of "password1"
        if (pwMatches()) {
            return password1;
        } else {
            return null;
        }
    }

    /*
        First Solution (FX):
    */

    public static void getPassword(String message) {
        run = true;
        showWindow(message,    // JFrame or FX-Window

            //    Function<char[],Void>
            password -> {

            // Working on the insert data in "password"
            if (pwMatches()) {
                Manager.setPassword(password1);
            } else {
                System.exit(0);
            }

            // POSITION 1
            return null;
        });

        // HERE MUST BE NOTHING! MUST ALL AT POSITION 1
    }

    /*
        Secound Solution (FX):
    */

    public static void getPassword(String message) {

        Thread t = new Thread(new RunableTemp(message);
        t.start();

        // Waiting till the user inserted the data to "password1"
        while(t.isAlive())
        {
            Thread.sleep(1000);
        }

         if (pwMatches()) {
            return password1;
        } else {
            return null;
        }
    }

    class RunableTemp implements Runable{

        ... void run()
        {
            showWindow(message);
        }

    }