Eclipse项目：Maven Eclipse插件设置了错误的JRE类路径容器

Question

I have an Eclipse Mars 2 Java8, Maven 3.5.4 based workspace. I build the project files with mvn eclipse:clean eclipse:eclipse , and watch the following maven output:

[INFO] Adding default classpath container: org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-**1.7**

The default JRE for the workspace isn't Java 7 , it is Java 8 , like you can see looking at the following Eclipse config file:

<workspace>\.metadata\.plugins\org.eclipse.core.runtime\.settings\org.eclipse.jdt.launching.prefs.

that contains the following data:

 org.eclipse.jdt.launching.PREF_VM_XML=<?xml version\="1.0" encoding\="UTF-8" standalone\="no"?>
        <vmSettings defaultVM\="57,org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType13,1538040823497*">
            <vmType id\="org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType">
                <vm id\="1431694854640" name\="jdk1.7.0_40" path\="C\:\\Program Files\\Java\\jdk1.7.0_40"/>
                <vm id\="1447417000092" name\="jdk1.6.0_45" path\="C\:\\Program Files\\Java\\jdk1.6.0_45"/>
                <vm id\="1538040823497" name\="jdk1.8.0_65" path\="C\:\\Program Files\\Java\\jdk1.8.0_65"/>
            </vmType>
    </vmSettings>

As you may notice by looking at the above configuration, the default VM has the vm id "1538040823497", which is named jdk1.8.0_65 , and resides in C\\:\\\\Program Files\\\\Java\\\\jdk1.8.0_65 .

This VM is correctly registered as Workspace Default in Eclipse Preferences, Java/Installed JREs, is marked as a "perfect match" within the Execution Environment JAVASE-1.8.

I cannot see anything why Maven Eclipse Plugin considers org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.7 as the correct choice, and not JAVASE-1.8 .

I already deleted all JREs and registered them newly.

Now there's exactly one 1.6, 1.7 and 1.8 Environment, each with a "perfect match", and 1.8 is checked as default (as you can see above).

I have to manually correct the project each time I generated it (Edit Build Path, change JRE library from 7 to 8), since all files using Java 8 features like streams or lambda functions signal compiler errors unless I assign the correct JRE manually.

I already tried and manipulate org.eclipse.jdt.launching.prefs , redefine all JREs, pray, curse or ask an Ouija board, to no avail, always Java 7 is assigned by the eclipse plugin (version 2.10, by the way).

Any ideas, anyone?

Answer 1

In your pom file, try to use this:

  <build>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.1</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
    </plugins>
  </build>

You may also reference this link:

https://dzone.com/articles/maven-eclipse-and-java-9

Or if all fails, try eclipse oxygen, a newer version (not the newest release but much better than Mars IMO) that has Maven Integration plugin pre-installed, all you need is to add a m2e-connector plugin.