[orestis]

Clojure does hot code reloading as a built in. You essentially send code to a running system and you change it. It’s enabled by a dynamic class loader. I wouldn’t say it’s common outside of Clojure though, the whole language and ecosystem is built around this concept.

To be clear: JVM enables the feature, so “technically” JVM allows hot code reload. Not sure how useful this is in practice for non-Clojure JVM users.

[eggsnbacon1]

Runtime code generation is a common optimization in java frameworks. End-users may never see it but the majority of popular frameworks use it under the covers.

Debuggers also use the functionality to allow live code editing and expression evaluation when paused on a breakpoint

[shawnz]

Eclipse, IntelliJ and Netbeans all support it out of the box for Java code.