Eclipse Kepler and JBoss Wildfly hot deployment

Using Eclipse, click twice on your WildFly Server to edit the following properties:

1. Publishing: choose "Automatically publish after a build event". I like to change the publishing interval to 1 second too.
2. Application Reload Behavior: check the "Customize application reload ..." checkbox and edit the regex pattern to \.jar$|\.class$

That's it. Good luck!

Both @varantes and @Sean are essentially correct, but these answers are not full.

Unfortunately the only way in a Java server environment to have full, zero-downtime hot deployment is to use paid JRebel or free spring-loaded tool.

But for small project there are some ways to speed up work by partial hot-deployment. Essentially:

1. When enabled option Automatically publish when resource change then changes inside *.html, *.xhtml files are immediately reflected as soon as you refresh the browser.
2. To make hot deployment work for *.jsp files too, then you should inside ${wildfly-home}/standalone/configuration/standalone.xml make following change:
   <jsp-config/>
   replace with:
   <jsp-config development="true"/>

restart the server and enjoy hot deployment of web files.

---

But when modifying *.java source files, then only partial hot deployment is possible. As @varantes stated in his answer, enabling Application Reload Behavior with regex pattern set to \.jar$|\.class$ is an option, but has serious downside: whole module is restarted, thus:

1. It takes some time (depending on how big is a module).
2. Whole application state is lost.

So personally, I discourage this solution. JVM supports (in debug mode) code-swapping for methods' bodies. So as long as you are modifying only bodies of existing methods, you are at home (zero downtime, changes are reflected immediately). But you have to disable automatic publishing inside server settings otherwise the application's state will still be destroyed by that republish.

But if you are heavily crafting Java code (adding classes, annotations, constructors) then unfortunately I can only recommend set publishing into Never publish automatically (or shutdown server) and when you finish your work in Java files, then restart by hand your module (or turn-on server). Up to you.

---

It works for small Java projects, but for bigger ones, JRebel is invaluable (or just spring-loaded), because all approaches described above are not sufficient. Also because of such problems, solutions like Rails/ Django /Play! Framework gained so huge popularity.