Question

I have a main program, in which GUI is based on swing and depending on one of four states the GUI elements have different parameters.

public class Frame extends JFrame implements Runnable {
Status status = 1;
...
@Override
public void run() {
    switch (status) {
        case 1:
        ...
        case 2:
        ...
}

public void updateGUI(Status status) {
   this.status = status;
   SwingUtilities.invokeLater(this);
}

And if I want to refresh the GUI invokes only updateGUI with appropriate parameter, and everything is fine. But the program also creates an additional thread, which after processing the relevant data should change the GUI main program. Unfortunately I can not in this thread call the method updateGUI (..).

I know that I can use invokeLater or SwingWorker to refresh but there are more than 10 elements so I would rather use the method udpateGUI ().

I will be grateful for any hint.

Answer 1

If you make the status field thread safe, then you can call setStatus directly from your background thread. To make the status thread-safe, put changes in a synchronize block, and make the variable volatile so updates on other threads become visible.

E.g.

public class Frame extends JFrame implements Runnable {
private volatile Status status = 1;
...
@Override
public void run() {
    switch (status) {
        case 1:
        ...
        case 2:
        ...
}

public void updateGUI(Status status) {
   setStatus(status);
   SwingUtilities.invokeLater(this);
}

private synchronized void setStatus(Status status) {
   this.status = status;
}

With these changes in place, it’s ok to call setStatus from any thread.