How to chain multiple SwingWorkers

I've got a big background task with some intermediate points where a user input is required.

E.g. buttonLoad_actionPerformed --> load, verify validity --> if outdated, ask user whether to update. If yes --> update, if no --> stop.

For now, I've coded this like this:

// load worker
SwingWorker<Status,Object> swLoad=new SwingWorker<> () {
    Validity doInBackGround() {
        return load(file);
    }

    void done() {
        Validity validity=get();

        switch (validity) {
            case UPTODATE:
                return;
            case OUTDATED:
                int res=JOptionPane.showConfirmDialog("File obsolete. Do you want to update it ?");
                if (res != JOptionPane.YES_OPTION) 
                    return;
                    
                // update worker
                SwingWorker<Boolean,Object> swUpdate = new SwingWorker<>() {
                    Boolean doInBackGround() {
                        return update();
                    }

                    void done() {
                        Boolean success=get();
                        if (!success) ....
                    }
                };
                
                swUpdate.execute();
        }    
    }
};

swLoad.execute();

However this can be become pretty unreadable if multiple steps are required.

What's the best approach for chaining conditional/optional SwingWorkers ?

I don't understand why you're doing anything in your done method.

Validity doInBackGround() {
    Validity validity = load(file);
    switch (validity) {
        case UPTODATE:
            return validity;
        case OUTDATED:
            int res= confirmOnEdt();
            if (res == JOptionPane.YES_OPTION) {
                Boolean success = update();
                //check the update and respond.
            }
    }
    return validity;
}

public int confirmOnEDT() throws InterruptedException{
    int[] container = {0};
    SwingUtilities.invokeAndWait( ()->{
            container[0] = JOptionPane.showConfirmDialog("File obsolete. Do you want to update it ?");
        }
    );
    return container[0];
}

One SwingWorker for the full set of tasks. The JOptionPane will block your background thread and wait for input. Also, you probably want to different return value than Validity.

Given that this is a bit of an obscure question, I'll give it a shot.

There are 2 items that stand out for me:

1. The shown function/method is rather lengthy
2. There is a lot of nesting going on

A simple solution to improve those is to split out code into separate methods.
Example, move the actionable code from the "OUTDATED" case into a separate method. Sure it's longer, but easier to follow.

public loadInWorker() {
	SwingWorker<Status,Object> swLoad=new SwingWorker<> () {
		Validity doInBackGround() {
			return load(file);
		}

		void done() {
			onLoad(get());
			}
		}
	};

	swLoad.execute();
}



private onLoad(Validity validity) {
	switch (validity) {
		case UPTODATE:
			return;
		case OUTDATED:
			int res=JOptionPane.showConfirmDialog("File obsolete. Do you want to update it ?");
			if (res == JOptionPane.YES_OPTION) {
				updateInWorker(); 
			}
	}
}



private updateInWorker() {
	SwingWorker<Boolean,Object> swUpdate = new SwingWorker<>() {
		Boolean doInBackGround() {
			return update();
		}

		void done() {
			Boolean success=get();
			if (!success) {
				onUpdateFailure();
			}
		}
	};

	swUpdate.execute();
}


private onUpdateFailure() {
	....
}

Edit + Opinion:
I'll add that I've never used that worker API. Looking at it, it seems quite convoluted. In my last days of Java development, I relied on ThreadPools for tasks with a short execution time and dedicated Threads for tasks with long execution time.
You could also write a wrapper for the SwingWorker call as you don't care about the internal types outside of it.
Example using bog standard Threads:

public loadInThread() {
	new Thread(this::loadInThread, "Load Thread").start();
}


private loadInThread() {
	switch (load(file)) {
		case UPTODATE:
			return;
		case OUTDATED:
			int res=JOptionPane.showConfirmDialog("File obsolete. Do you want to update it ?");
			if (res == JOptionPane.YES_OPTION) {
				new Thread(this::updateInThread, "Update Thread").start();
			}
	}
}



private updateInThread() {
	if (!update()) {
		// Update Failure code goes here
	}
}