Updating JPanel during a loop.

Question

Here's the deal: my first class (first file) which extends a JFrame, creates a JFrame and adds some JPanels to it (with buttons, JTextFields etc), after i press one button it creates an instance of a class Algorithm that is in another file, and calls a function solve() from that class, which counts some things. In that function (the start() one) there are 2 loops, and it returns a stack. The thing is I want a JTextField from that JFrame to be updated with every new loop (so it would show numbers 1,2,3,4,etc while the function was being executed). If they were in a single file than there would be no problem (simply message.setText(loopNumber+"");), but since they are in different files I have no idea how to do it. Should I try making a new thread for the solve() function or what?
It would be something like this, file1 (tho the new Algorithm part isnt in main() but it is executed after a button is pressed):
public class Frame extends JFrame{
         variables
         private JTextField message; // this one is in one of the JPanels attached to the JFrame
main(){
       JFrame frame = new JFrame();
       new algorithm = new Algorithm(passes some variables);
       algorithm.solve();
}Second file:
public class Algorithm{
       some variables,
       constructor etc;
       int numer = 0;
       public void solve(){
                for(int i=0; i < 10; i++){
                          numer += 1;
                          something happens here;
}And I want to change the "message" whenever "number" changes.

Answer 1

Someone told me I should make a new thread for the soultion() in order to "repaint" the JPanel that contains the "message"...Not for setting a text field, you shouldn't. But you're getting dangerously close to mashing up your GUI and "business" logic with inappropriate relationships. You may want to have a look at the Observer pattern, where your algorithm can notify any observers of state changes, and the observers can handle that information as they see fit.
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