Update a JLabel from another thread without having to separate all my processes on threads?

Question

I'm developing a big project on Java Swing. It has a database connection, external devices managing and sd-cards processing.

I currently have a lot of heavy processes that run on the EDT thread, and making separated threads for all of them is a long long task that I'm trying to escape... Besides, It would probably introduce a lot of concurrency problems that I am not willing to handle.

The thing is that I want to introduce a loading JLabel with a loading gif while the long busy tasks are being processed. It is also important to highlight that I want my whole swing interface to be blocked while the long tasks are being done, just like it happens now, EXCEPT for the loading label.

Is there a way to actualize that label from another thread?

Answer 1

If you care about creating a good user experience, there really is no escaping using SwingWorker or similar, to offload work form the event dispatcher thread (EDT). If you need to really need to "block" the UI, you should use a JDialog with a progress bar or similar.

The short answer to your question is no. The Jlabel must be instantiated and added from the EDT.

However, you should be able to add the JLabel, you just have to make sure you do it before the long-running blocking tasks starts. Then remove it after it is done.

Anyway, this is a hack, and a lazy workaround for doing the right thing, and is not recommended. You might experience that you spend more time working around the issue and pulling your hair, than just do it properly with SwingWorkers.