Thread: Regarding working with different objects and passing information

I received this private message from delta2w today, and suggested that he post it in the general forum, but since he has yet to do so, I've taken the liberty of posting it for him:

Originally Posted by delta2w

Hi,
I read your post today regarding updating a JTextArea from another class. I am having a similar issue but being very recent to JAVA I didn't fully know how to implement your answer and hoped you wouldn't mind explaining it to me in simple terms.

What I am trying to do is as follows:
I am working in NetBeans and I have two classes, a 'MyGui' class with a JFrame with a number of JTextAreas, JLists etc and a second 'updater' class. I wish to be able to set/append the text in any of the JTextAreas, JLists etc from the updater and other future classes. Both classes are in the same package and access is set to default for all textareas.

I have created a setText(String str) method for JTextArea1 in the MyGui class which takes a String param and uses JTextArea1.setText(str); and has a message popup and have called this from the updater class using:
MyGui gui = new MyGui();
gui.setText("Test Text");
but the text does not appear although the message does. I feel that this is likely due the same reason you mentioned and I am possibly creating a new instance of MyGui which is not visible.

How do I pass a reference to the constructor to enable this to work for all of the JTextAreas and JLists? The current MyGui constructor simply contains initComponents();

I also read that it might be due to the EventDispatchThread and require swingutilities.invokeLater. I have tried this but get the same results with just the popup but no change in the textarea text.

I really appreciate any help/advice you could offer.
With Thanks

Thanks. I solved it simply by adding a second constructor to updater class as follows:
public Updater(MyGui gui) {
this.gui = gui;
}
Then passed a reference to the original MyGui instance when calling a method in the updater class to update the text
Updater updater = new Updater(MyGui);
updater.setNewText("new text");
Works as needed.