Convert XAP to JAR

There doesn't seem to exist any way how Windows Phone apps (.xap) could be just simply converted to Java app (.jar). That's a job for a programmer to rewrite the app from one platform to another using a specialized IDE. It is unlikely that xap to jar conversion can be achieved using some kind of converter.

Simply put, it is impossible to convert XAP to JAR directly.
Thus, there is no so-called xap to jar converter or a free online .xap to .jar converter to be found.