CODEWITHSUNDEEP
maven
Eldad Assis
Eldad Assis

Reputation: 11045

Maven deleted class still in jar if mvn clean not run

In an effort to speed up my maven build time, I want to run mvn install and not mvn clean install.
If I do this, and a source file was removed (in VCS and I got this change after updating my copy), maven will still pack the old file (since it's still under the target folder).
I'm aware of this thread and others similar, but I'm not satisfied with the end result.

I assumed that maven is "smart" enough to pick up only changes and do a real incremental build, but this behavior breaks this assumption...

Does anyone have an idea on how to enjoy a true incremental build with maven without using the clean life-cycle?

Upvotes: 0

Views: 1660

Answers (1)

Software Engineer
Software Engineer

Reputation: 16100

Maven runs through it's lifecycle, running external tools through plugins at various points in the process. You can choose where this process begins, and the recommended starting point is clean. We recommend this because maven knows nothing about your source-code -- it doesn't even know whether it's java or C++ -- and it doesn't have to. It just knows that it should invoke the configured compiler (javac for example) on the configured source directory as soon as it reaches the compile step of the lifecycle.

Your compiler knows about source, so if something is to blame here, blame the compiler. However, most compilers will not delete a compiled artifact just because a source file has been removed, because it doesn't know that this artifact isn't going to be linked (referenced) later -- as far as the compiler is concerned, it's only interested in artifacts relating to source files. This is probably the only tool that looks at your source (except maybe some static code analysis tools and perhaps some documentation tools such as site and javadoc).

Maven will proceed after compilation to run your tests, and if they pass it'll enter into the packaging step. Packaging is again an external tool (jar for example), configured through a plugin. In the case of jars or wars, this takes the contents of the target directory and zips them up into a jar or war according to the configured instructions. Again, there is no part of this that needs to know if a file was removed from the source or not -- in fact, it doesn't even look at the source at this point, so how would it know that a file was removed.

My point is, you're assuming too much of your development environment. It has no way of knowing that a file in a target directory is unneeded, unless you go to great lengths to tell it that this is so. That's why there is a clean step in the first place.

As an aside, clean shouldn't be taking a lot of time. If it is, perhaps you should refactor your project into more modules.

Upvotes: 1

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