Question

I have a java app in which I use a thread. My thread runs every 20 seconds but, when it runs it kind of blocks the UI … i. e. whenever the thread is running and the user clicks on button on anything on UI it doesnt respond sometimes.

Could anyone tell me a solution to this problem.

Answer 1

in java Swing, any change made to the state of the UI should be done in a single pre-existing thread called the EDT (event-dispatcher thread).

if that’s not the case, you typically experience weird glitches / freezes. one of the most common symptom is that part of the UI becomes gray (except since java 1.6, where the ui is still painted like before, but unresponsive).

the good way to go is to use a dedicated method to queue your changes to the UI in the EDT :

SwingUtilities.invokeLater(Runnable toRunInEDT);

note that if you call invokeLater, the runnable is executed after all currently queued event have been dispatched. that means that the next line of code could be executed before the code in the runnable. there is a synchronous version as well (which should not be executed from the EDT):

SwingUtilities.invokeAndWait(Runnable toRunInEDT);