Best Debug Technique

Hello,

I have a java Gui being built by ant and then run by an ant task. What is the best way to debug it?

1. set the jvmargs to turn on debuging when the gui is executed then use intellij to remotley debug it?
2. Set the intellij output path to the build dir created by ant so i can debug directly from intellij without having to compile from intellij

Which would you recomend
Thanks,
Joe