I'd like to know which Java web application frameworks provides a "hot reload" capability, i.e., it allows to develop applications and has them redeployed on the server "almost instantly" (i.e., in less than a few seconds).
In the Java world, Play! does that out of the box, but what I'm looking for is a more exhaustive list.
Other examples that I'm aware of include: Nuxeo WebEngine, provided you're using Eclipse and the right plugin, or, in the Python world, Django and Pylons (when using the --reload option).
If someone might be interested after those months:
you can configure jetty so that it will hot deploy your compiled classes (eclipse + netbeans have the compile on save feature). With maven you can type mvn jetty:run after this config in your pom.xml:
<plugin>
<groupId>org.mortbay.jetty</groupId>
<artifactId>maven-jetty-plugin</artifactId>
<version>${jetty.version}</version>
<configuration>
<scanTargets>
<scanTarget>target/classes/</scanTarget>
</scanTargets>
<scanIntervalSeconds>1</scanIntervalSeconds>
</configuration>
</plugin>
This can be done without the use of jrebel and it means: do a change in the IDE + save it + go to your browser + F5 => you are done!
With that feature e.g. wicket or vaadin are hot deployable (but others too!)