Challenger supports programming in Java by supporting Java Servlets as well as making it possible to call on Java modules from Pike. For the Java support to work Java JDK 1.2 must be installed and Pike must have been compiled with Java support, as explained in the Servlets page in the Administrator manual.

Java within Challenger takes advantage of the tight integration between Pike and Java. The Pike interpreter will start and control the Java interpreter through Java native method invocation. Both Pike and Java is run within the same process, in different threads. This integration means that the penalty for calling a methods in Java from Pike is extremely low. It becomes possible to mix the languages without worrying about performance.

The main use for this tight Pike/Java integration in Challenger is to write modules in Java. Every Challenger module needs to be written in Pike, but by making a small wrapper module in Pike that calls methods in Java the effect will be that of a modules written in Java.