What causes imported Maven project in Eclipse to use Java 1.5 instead of Java 1.6 by default and how can I ensure it doesn't?

Question

I imported a Maven project and it used Java 1.5 even though I have 1.6 configured as my Eclipse default Preferences->Java->Installed JREs.

When I changed the Maven project to use the 1.6 JRE it still had the build errors left over from when the project was using Java 1.5 (I described these build errors earlier in: I have build errors with m2eclipse but not with maven2 on the command line - is my m2eclipse misconfigured?)

I'm going to delete the project and try again but I want to make sure this time that it uses Java 1.6 from the start to see if this eliminates the build problems.

How do I make sure the project uses Java 1.6 when I import it?

Answer 1

The m2eclipse plugin doesn't use Eclipse defaults, the m2eclipse plugin derives the settings from the POM. So if you want a Maven project to be configured to use Java 1.6 settings when imported under Eclipse, configure the maven-compiler-plugin appropriately, as I already suggested:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-compiler-plugin</artifactId>
  <version>2.1</version>
  <configuration>
    <source>1.6</source>
    <target>1.6</target>
  </configuration>
</plugin>

If your project is already imported, update the project configuration (right-click on the project then Maven V Update Project Configuration).