All Java developers will be familiar with the javac tool for compiling source code to bytecode, which is used by the JVM to run Java programs. Smart Java compilation, also referred to as Smart Javac and sjavac, adds a smart wrapper around the javac process. Perhaps the core improvement added by sjavac is that only the necessary code is recompiled. Necessary code, in this context, is code that has changed since the last compile cycle.

This enhancement might not get developers excited if they only work on small projects. Consider, however, the tremendous gains in efficiency when you continuously have to recompile your code for medium and large projects. The time developers stand to save is reason enough to embrace JEP 199.

How will this change the manner in which you compile your code? It probably won't, at least not yet. Javac will remain the default compiler. While sjavac offers efficiencies regarding incremental builds, Oracle has deemed it to not have sufficient stability to become part of the standard compilation workflow.