Maven project compiles but there are missing imports in the workspace

Question

I'm using eclipse Kepler with the m2e plugin and I want to modify a maven project and compile it. I first converted it to a maven project with Configure -> Convert to maven project, but there were still many missing imports. When I use Run as... -> Maven install the project compiles.

How can I fix the missing imports?

Answer 1

Tell m2e to update the project: Context menu of the project / Maven / Update Project...

m2e will then read the POM again and update the classpath and build the project again.

Make sure you have this in your .classpath file:

<classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER">
    <attributes>
        <attribute name="maven.pomderived" value="true"/>
    </attributes>
</classpathentry>

Note: The actual syntax might be slightly different depending on the m2e version that you use.

Another common pitfall is the scope provided:

provided
This is much like compile, but indicates you expect the JDK or a container to provide the dependency at runtime. For example, when building a web application for the Java Enterprise Edition, you would set the dependency on the Servlet API and related Java EE APIs to scope provided because the web container provides those classes. This scope is only available on the compilation and test classpath, and is not transitive.

Note the last part: not transitive

This means you depend on POM A which says "I need X:Y:Z, scope provided". Your project will see this dependency but it won't be on your classpath at all.

To fix this, copy the dependency into your project with the same scope (provided).