Java : Catch exception in different thread

Question

I'm developing a Swing application that also does use a REST-API. I'm using Jersey to accomplish this.

I want the user to input a URL into a TextField and would like to give him some feedback if the URL is malformed or anything. I'm using URI as a basis to store the URL and am able to catch any problems that arise with that and give the user some informations.

 } catch (URISyntaxException ex) {
        MainClass.write2Log("URL wrong : '" + baseURL + "'");
        }

Now, when the URL has the right format, but simply doesn't resolve, I get this exception :

Exception in thread "AWT-EventQueue-0" javax.ws.rs.ProcessingException:
java.net.UnknownHostException: sx.dddsds.ded
at org.glassfish.jersey.client.HttpUrlConnector.
apply(HttpUrlConnector.java:205)

So my questions is this : How can I 'catch' this exception when I don't have the Object that throws this exception?

Thanks in advance !

Answer 1

Exceptions travel up the call stack on the thread they were thrown in; they don't cross threads. If you want to catch an exception, you need your try-catch block somewhere in the stack trace that you didn't post in your question.

Looking at the lines you did post, it's looking like you're trying to execute a long-running operation (an HTTP request) on the event thread; it should be running somewhere else.

Answer 2

You can set it for particullar (for example current, or any other Thread instance) thread or globally for all uncaught exceptions:

Thread.setDefaultUncaughtExceptionHandler( ... );
Thread.currentThread().setUncaughtExceptionHandler( ...);

Starting a new thread by Thread you can set exception handler, and if you start new thread with executor you can set your custom thread factory, that will set exception handler.