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?

user_93982 0
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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?

build-error m2eclipse eclipse maven-2 java
13 Answers

Simplest solution in Springboot

I'll give you the simplest one if you use Springboot:

<properties>
  <java.version>1.8</java.version>
</properties>

Then, right click on your Eclipse project: Maven > Update project > Update project configuration from pom.xml

That should do.

user_6150250

In case anyone's wondering why Eclipse still puts a J2SE-1.5 library on the Java Build Path in a Maven project even if a Java version >= 9 is specified by the maven.compiler.release property (as of October 2020, that is Eclipse version 2020-09 including Maven version 3.6.3): Maven by default uses version 3.1 of the Maven compiler plugin, while the release property has been introduced only in version 3.6.

So don't forget to include a current version of the Maven compiler plugin in your pom.xml when using the release property:

<properties>
    <maven.compiler.release>15</maven.compiler.release>
</properties>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.1</version>
        </plugin>
    </plugins>
</build>

Or alternatively but possibly less prominent, specify the Java version directly in the plugin configuration:

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.1</version>
            <configuration>
                <release>15</release>
            </configuration>
        </plugin>
    </plugins>
</build>

This picks up Line's comment on the accepted answer which, had I seen it earlier, would have saved me another hour of searching.

user_63760770

If you want to make sure that newly created projects or imported projects in Eclipse use another default java version than Java 1.5, you can change the configuration in the maven-compiler-plugin.

  • Go to the folder .m2/repository/org/apache/maven/plugins/maven-compiler-plugin/3.1
  • Open maven-compiler-plugin-3.1.jar with a zip program.
  • Go to META-INF/maven and open the plugin.xml

  • In the following lines:
    <source implementation="java.lang.String" default-value="1.5">${maven.compiler.source}</source>
    <target implementation="java.lang.String" default-value="1.5">${maven.compiler.target}</target>

  • change the default-value to 1.6 or 1.8 or whatever you like.

  • Save the file and make sure it is written back to the zip file.

From now on all new Maven projects use the java version you specified.

Information is from the following blog post: https://sandocean.wordpress.com/2019/03/22/directly-generating-maven-projects-in-eclipse-with-java-version-newer-than-1-5/

user_12016260

To change JDK's version, you can do:

1- Project > Properties
2- Go to Java Build Path
3- In Libraries, select JRE System ... and click on Edit
4- Choose your appropriate version and validate

user_97580660
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