Intellij: Error:java: error: release version 5 not supported

Maven setup: Exemplary pom.xml for Java 11

Ensure Maven supports Java 11 by modifying your pom.xml:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.8.0</version> <!-- We are not living in stone age anymore -->
    <configuration>
        <source>11</source>
        <target>11</target> <!-- Just keep the pace-->
    </configuration>
</plugin>


This config guarantees source and target bytecode compatibility with Java 11. Cross-verify with IDE settings for Maven project compilation:

Settings > Build, Execution, Deployment > Compiler > Java Compiler

Here, set "Per-module bytecode version" to 11.

JDK Upgrade: Keep your sword sharp

If you're lagging with outdated JDK, you might need to spend some time downloading a fresh JDK. Make sure it's the same version you specified in pom.xml. Use trusted sources like Adoptium for downloads:

• Head to Adoptium & choose JDK version.
• Follow instructions to install.
• Setup the newly minted JDK in IntelliJ (Project Structure).

Ctrl+Alt+Shift+S > Platform Settings > SDKs > Add New JDK

IntelliJ Compiler Settings: The Magic Wand

Check the Java version of the IntelliJ compiler to ensure it's aligned with your system preferences:

Settings (Preferences on macOS) > Build, Execution, Deployment > Compiler > Java Compiler

Here, set the "Project bytecode version" to 11 and save changes.

Encoding & Consistency: Avoid Alien Characters

Ensure your pom.xml has project.build.sourceEncoding set to UTF-8 for consistent encoding, avoiding any alien invasion (unwanted special characters):

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <!-- No alien invasion please -->
</properties>


Correct Syntax: groupId & artifactId

Ensure groupId and artifactId for maven-compiler-plugin is correct:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId> <!-- No need to forge it -->
</plugin>


This avoids plugin resolution going wild, ensuring authentic plug-in usage.

Maven vs IntelliJ: Bytecode Version Face-off

Check that Maven project's bytecode version doesn't squabble with Java JDK version. IntelliJ IDEA lets you customize compiler settings per project - use it for harmonious Maven collaboration:

Maven Projects > Your project name > Lifecycle > compile

Examine the output - ensure consistency.

Outdated Java Versions: Leave them in the Past

Beware of ancient versions while setting project. Java 5 has retired; modern projects aim for Java 6 or higher, with preferential treatment for 1.8 (Java 8) or Java 11 due to wide acceptance and compatibility.

Unique Project Requirements: Tailor your Settings

Every project is unique. When necessary, you can specially tailor maven-compiler-plugin settings to meet your project's idiosyncratic needs, ensuring project requirements aren't breached.