I'm no expert on Grails or Groovy, but you need to remember that in many ways Groovy
is Java underneath - you can use pure Java inside your Groovy code, call Java packages etc etc, and it all compiles down to Java byte code underneath. Groovy is a purely JVM-based language (unlike JRuby or Jython which are JVM implementations of other languages). This means you can apply all your Java knowledge but take greater advantage of Groovy as you become more comfortable with the language.
One area where Groovy might have a disadvantage is if you are using a lot of its dynamic features (duck-typing, dynamic code, meta-programming etc), because this can demand more processing at run-time, so performance may be slower. On the other hand, you can often develop Groovy code much faster and more reliably than the equivalent Java code, so speed of development may be more important for you than speed of execution.
Grails is a "code by convention" web application framework (similar to Rails or Django) implemented in Groovy and built on top of common Jave EE tools like Spring, Hibernate etc. Again, it all compiles down to Java byte code underneath, you can mix in Java code/classes, and the resulting web application is a normal WAR that you can deploy to your
servlet engine/Java EE server as appropriate.
Grails makes a lot of use of Groovy's dynamic features, so it may not perform as fast as a well-engineered pure Java solution, and you need to code with the conventions to make best use of it. But as with Groovy, it may be that the speed of development and the comparative simplicity (maintainability) of the code is more important to you than execution speed.
Anyway, I'm sure there are plenty of JavaRanchers with more Groovy/Grails experience who can give you an expert opinion.
1
