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 The JDK is being used is different than expected.
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 Barrie Treloar
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 24 April 2009
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Summary

  After running <<<mvn eclipse:eclipse>>> your project's are using a different JDK than expected.

Checklist

* Correct version of Java source specified in <<<maven-compiler-plugin>>>?

  For example, setting the source to 1.6 compliance?

+---
<plugin>
   <artifactId>maven-compiler-plugin</artifactId>
   <version>2.0.2</version>
   <configuration>
       <source>1.6</source>
       <target>1.6</target>
   </configuration>
</plugin>
+---

* The default JDK defined in eclipse matches what you expect?

  In eclipse's preferences check Java > Installed JREs and that the selected one is the version you expect.

* The Execution Environment for the expected version is bound in eclipse preferences?

  In eclipse's preferences check Java > Installed JREs > Execution Environment has a bound value for compatible JREs.

  For example, JavaSE-1.6 should have "perfect match" or an Installed JRE selected as being compatible.

* The <<<.claspath>>> specifies the correct Java container?

  Open the <<<.classpath>>> file and look for the <<<<classpathentry kind="con">>> entry.

  It should either be using the default JRE:

+---
  <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>
+---

  Or it should be a specified execution environment:

+---
  <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.6"/>
+---