Static analysis allows code quality tools to recognize patterns that indicate bugs or other coding errors. Agile practices suggest that finding and fixing such bugs early in the development pays dividends by raising the quality of the code base.

In a recent blog post, Get Medieval On Your Code, Sun engineer Tom Ball suggests that you take advantage of the most readily available code quality tool, the compiler itself:

[If you] enable all compiler warnings and tell the compiler to treat them as errors, all of a sudden, those "minor" cleanup issues one never has time for now demand immediate attention. This actually saves time in the long run, because once you go through the work of cleaning up all the existing warnings, any new problems can be quickly caught while the new code is being developed (rather than having to scramble after the product ships).

Ball notes that Java compilers have an extensive set of warning messages that can be enabled:

In Java 5 the javac compiler added the -Xlint option with several types of checks, which were significantly expanded in Java 6. The Jikes compiler has a similar option called pedantic compilation (+P).

With the new Java Compiler API, JSR 199, developer tools will increasingly integrate with the compiler, for instance, by compiling code while the developer types in the editor, keeping a constant binary tree of the code in memory. That feature is already implemented in the upcoming NetBeans 6 release. Once the compiler is used throughout the editing process, compiler warnings can give instant feedback on new code, according to Ball.

How seriously do you take compiler warnings in your projects?