[Building Sakai] import maven project into eclipse unable edit the code

[Luke]

Hello All,
   I run the following command in my terminal and  follow the promots:
mvn archetype:generate -DarchetypeGroupId=org.sakaiproject.maven-archetype
-DarchetypeArtifactId=sakai-spring-maven-archetype -DarchetypeVersion=1.2
-DarchetypeRepository=https://source.sakaiproject.org/maven2/

Then output the maven project.
 I import the project into eclipse by Import->Existing Maven Projects. Here my
problem is "The compilation unit is not on the build path of a java project"
message comes when I editing the coding. Auto completion not working. Kindly let
me know how solve this problem...

Note: I searched in google , but still I am not clear in that.