Java version automatically change to java 1.5 after maven update
Had the same issue when I installed Java 9. My project would default to J2SE-1.5 Execution Environment. Strangely, Java 9 compliance level is not referenced like previous versions, i.e. "1.8", but as "9". So I had to provide my properties and Maven compiler plugin config accordingly:
<properties>
<maven.compiler.source>9</maven.compiler.source>
<maven.compiler.target>9</maven.compiler.target>
</properties>
and
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>9</source>
<target>9</target>
</configuration>
</plugin>
This seems to have solved the problem. Works for versions 9 and above.
The root-cause of this issue is that if for any reason Eclipse's cannot resolve a valid value for the maven.compiler.source
property when generating/updating the .classpath file from the pom, it will simply default to using org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/J2SE-1.5
.
As expertly answered by @jorge-campos, there are multiple ways to set that property.
However, Jorge's answer didn't appear to work for me. Here were my settings:
<properties>
<javaVersion>1.8</javaVersion>
<maven.compiler.source>${java.version}</maven.compiler.source>
<maven.compiler.target>${java.version}</maven.compiler.target>
</properties>
...
Exactly. ${java.version}
is never going to resolve to the (completely different) property javaVersion
and Eclipse ignored the property and used the default.
Which brings me back to the "for any reason" part I opened with; developer stupidity can be one of those reasons.
Open your pom.xml
file and add the following lines on it:
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
Where 1.8
is the Java version of your current JDK/JRE. Another way of doing this is adding a <build>
with the maven-compile-plugin
as:
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.2</version> <!-- or whatever current version -->
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
If you are looking for a way to make it work with Java versions 9+ please take a look at @JDelorean's answer.