Problems with mainThread

Question

im trying to solve that problem for days. My program editing images. im not using multithreading.

i am using a function (private void console()) that writes formatted text in a JTextPane. i have a class called ImageWork() that works with my pictures.

my problem: i call first the console("start with work") function, after that i call a function of my class to editing an image (it takes some time). then i called another time my console("finish") function. i have tried many things that the method to editing the image wait till the console function is ready without success :(. so every time i call the 3 functions first the image will be edited, then the console function writes in my textpane both texts.

private void color2gray()             
{           
       console("start")       
    try         
       {  
        myImg.color2gray();   
        console("success");   
        repaint();    
    } 
    catch (Exception e) 
    {
        console("no success");
    }

the program works fine. my problem is that i want that text in my console (JtextPane) that the function starts now and then the function color2gray starts because that function could take one minute with big pictures.

i have already tried things like change console return type to boolean and call that:

  while (!(console("start")) {};

I would be pleased if there finds someone an solution for that problem. Thanks

console() code:

private void console(String str,boolean fehler)         
{               
    time=new GregorianCalendar();

    String help=time.getTime().toString();
    help=help.substring(0,19);

    doc = (StyledDocument) console.getDocument();
    Style style = doc.addStyle("StyleName", null);

    StyleConstants.setForeground(style, Color.black);
    try { doc.insertString(doc.getLength(),help, style); } 
    catch (BadLocationException e) { e.printStackTrace(); }

    if (fehler) StyleConstants.setForeground(style, Color.red);
    else StyleConstants.setForeground(style, new Color(0,125,0));

    try {   doc.insertString(doc.getLength()," :  "+str+"\n", style); } 
    catch (BadLocationException e1) { e1.printStackTrace(); }
}

Answer 1

What is the name of the thread that invokes color2gray()? Add this to the first line of that function to find out:

System.out.println("Thread = " + Thread.currentThread().getName());

You may see an output like this:

Thread = AWT-EventQueue-0

Which means the code is running on the "event thread". This should be the only thread that modifies Swing/GUI components. AND this thread should NOT do long-running work. If this is the event thread, then you need to do your long work in the background.

change

myImg.color2gray();

to

Thread t = new Thread() {
    @Override
    public void run() {
      myImg.color2gray();
  }
};
t.start();

As a start. And read more about the swing event thread:

http://docs.oracle.com/javase/tutorial/uiswing/concurrency/dispatch.html http://en.wikipedia.org/wiki/Event_dispatching_thread