Maven project not being treated as Java in Eclipse

Question

I'm working on a project that has lots of different Maven projects. I've been doing a bunch of JUnit testing on these projects, and usually this goes well. I open up Eclipse, right click in package explorer->Import... Existing Maven Projects and I'm able to import the project fine. I can build, drill down to src/test/java... Right click on the file and do a Run As JUnit test. Every now and then though, I can't get this to work. If I right click to do a Run As, all I get is AspectJ/Java application. There's no JUnit tests.

I noticed that the icon next to the project folder only has an M and a folder icon, whereas with projects that do work, there's a folder, M, AND a AJ. I've also noticed that it doesn't seem to sort the files into their packages like normal Java projects. It seems like it's not treating the project as an AspectJ project. How do I get Eclipse to recognize this Maven project as a Java project?

Answer 1

Several of the existing answers should work, but those suggesting to add a Java facet will only work if your project already is of (or you want to convert it to) a faceted nature, and the one suggesting you change your pom.xml will only work if you then re-import your project as a maven project.

If you'd like to "fix" your existing project, i.e. add a Java nature without converting it to faceted form and without deleting and re-importing, just edit your .project file (externally, or with the Navigator view in eclipse, as it won't show up in your package explorer) and add the java builder and java nature to the existing maven builder/nature:

<?xml version="1.0" encoding="UTF-8"?>
<projectDescription>
    <name>yourprojectname</name>
    <comment></comment>
    <projects>
    </projects>
    <buildSpec>
        <!-- add this build command -->
        <buildCommand>
            <name>org.eclipse.jdt.core.javabuilder</name>
            <arguments>
            </arguments>
        </buildCommand>
        <!-- this would've already been there -->
        <buildCommand>
            <name>org.eclipse.m2e.core.maven2Builder</name>
            <arguments>
            </arguments>
        </buildCommand>
    </buildSpec>
    <natures>
        <!-- add this nature -->
        <nature>org.eclipse.jdt.core.javanature</nature>
        <!-- this would've already been there -->
        <nature>org.eclipse.m2e.core.maven2Nature</nature>
    </natures>
</projectDescription>

Note the different capitalisation (javabuilder but maven2Builder, javanature but maven2Nature).

As soon as you save, it should re-build automatically. You may have to manually add any source folders (Project properties -> Java Build Path -> Source tab -> Add Folder....