Compilation unit is not on the build path of a Java project

Question

I joined an SVN server and checked out the source files a project from that server. In the Eclipse editors, when I hit Ctrl + Space, I got the following error message:

This compilation unit is not on the build path of a Java project

What should I do to solve this problem?

Solution

Read this guide on how to use maven projects with eclipse

http://maven.apache.org/guides/mini/guide-ide-eclipse.html

Taken from the above link :

Reason why you get that notice :

Eclipse needs to know the path to the local maven repository. Therefore the classpath variable M2_REPO has to be set.

Solution

Execute the following command:

mvn -Declipse.workspace=<path-to-eclipse-workspace> eclipse:add-maven-repo

Restart your Eclipse IDE (if you already have it open) for this change to take effect. You can also define a new classpath variable inside eclipse: From the menu bar, select Window > Preferences. Select the Java > Build Path > Classpath Variables page

For Simple Projects :

If you have a simple java project which is made up of only one module, using eclipse is very simple. To generate the eclipse project files from your POM you execute the following command:

mvn eclipse:eclipse

If you have created or checked out the project with eclipse, you only have to refresh the project in your workspace. Otherwise you have to import the project into your eclipse workspace (From the menu bar, select File >Import >Existing Projects into Workspace). In the latter case the project (directory) should not be located in your workspace, because eclipse might come into trouble, especially if you want to use eclipse as the scm client.

For a more detailed explanation refer the above link.

Comments

[Aaron Franke]

[ERROR] Could not find goal 'add-maven-repo' in plugin org.apache.maven.plugins:maven-eclipse-plugin:2.10 among available goals clean, configure-workspace, eclipse, help, install-plugins, myeclipse, myeclipse-clean, rad, rad-clean, remove-cache, resolve-workspace-dependencies, to-maven -> [Help 1]