Re: How to change JPanels?

Patricia Shanahan <>
Fri, 18 Feb 2011 11:11:37 -0800
On 2/18/2011 7:14 AM, Eric wrote:

The task of the SwingWorker was to update the JFrame display to make
panel 1 visible, then wait 3 seconds, then make panel 2 visible.
I put some trace lines in where it started each task to show "making
panel 1 visible" then "making panel 2 visible".
Starting them one right after the other shows they ran at the same
"making panel 1 visible"
"making panel 1 visible"
"making panel 2 visible"
"making panel 2 visible"

Could you explain why you see this as evidence that they ran at the same
time? Wouldn't you get exactly the same output sequence if "making panel
1 visible" were done first, followed by "making panel 2 visible"?

Remember that making a panel visible is a very quick action, completed
once the GUI state has been changed to make the panel visible. After
that, the EDT is done with it, and can go get the next message from its

Making panel 1 visible was actually done in the initial EDT thread, in
the actionPerformed method of a menu item listener.

It was done in the one and only EDT.

The 3 second wait was done in the SwingWorker object's doInBackground.
Making panel 2 visible was actually done in the SwingWorker's done

Which also runs in the one and only EDT.


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