Automatic do background work in panelX when you cardLayout.show(panelX)?

Question

Let me first explain what I try to accomplish
+Panel 1: A form that allow people to enter username and password to connect to a database
+Panel 2: Use the connection that just created in panel1 to access database and load data into a JcomboBox
+ContentPane that hold these 2 panel (Layout: cardlayout)
+Top container is a JApplet
So when the program load, I will cardlayout.show(Panel1), then if the user press a "submit" button, I will cardlayout.show(Panel2). Simple enough. Panel2' s job is to silently access a database using the connection that is created in panel1 a load some information onto a JComboBox. My question is how do I design so that when the user press that "submit" button, it detects that now panel2 is in focus so invoke my loadData() that access the database and load data onto the JcomboBox?
Right now i have it so that when panel2 show, the user have to click the "load" button to load information. However, I wish to change that. So please give me some advice.
Thank you very much and happy thanksgiving

Answer 1

JohnBrand wrote:
A clarifying question - should the uploading and downloading be done on a SwingWorker background thread or should it be on a non-SwingWorker thread? You can do it either way. It's fielder's choice here.
Don't the SwingWorker threads end up on the Event Dispatch Thread?Some methods of SwingWorker are always called in the EDT including the done method and the process method, but the main method, doInBackground, in fact the only method that is required in a SwingWorker-extended class is done off of the EDT. Having methods that reliably work on and off of the EDT is what makes using a SwingWorker object an easier way to create background threads in Swing vs. creating a roll-your-own background thread.