The best replacement for javac is eclipse compiler.

The best alternatives to javac are rated as following:
★★★★★  eclipse compiler
★★★★  gcj
★★★  ecj
★★  javacc
★  javacpl
★  javaw
★  jikes

Your alternative for javac is not listed? Suggest!
Speaking about javac, one probably shouldn't forget about classpath.

Other search terms related to javac and their ratings are:
★★★★★ classpath
You have in mind a companion for javac and it is not yet here? Propose!



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javac
eclipse compiler
gcj