Question

Eclipse Juno Release
Window / Preferences / Java / Installed Jres
shows two installed Jres.
jdk1.7.0_07 and jre7.

I get the following error when trying to clean and process-classes with maven:

Failed to execute goal org.apache.maven.plugins:maven-compiler- 
plugin:2.4:compile (default-compile) on project reputation: Fatal 
error compiling: tools.jar not found: C:\Program 
Files\Java\jre7\..\lib\tools.jar

I added tools.jar as external jar already, out of desperation, but it didn’t help. Why is maven trying to use the other JRE?

EDIT:

Compiler plugin excerpt from pom.xml

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>2.4</version>
    <configuration>
        <source>1.6</source>
        <target>1.6</target>
    </configuration>
</plugin>

Answer 1

You need to set your JAVA_HOME environment variable to the JDK directory.

EDIT:

In your installed JREs preferences window in Eclipse remove the JRE and select the JDK. Also make sure that your project is set to use that JRE library (Right-click on the “JRE System Library” under your maven project structure in the explorer and set it as the “Execution Environment”)