How to Specify Java Version in Maven: Properties vs. Compiler Plugin?

Specifying Java version in Maven: Properties vs. Compiler Plugin

Java version specification in Maven allows setting the required JDK version for project compilation. There are three main ways to do this: using Spring Boot feature, Maven compiler plugin with source and target, or Maven compiler plugin with release.

Spring Boot (Not recommended for general use)

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

This method is exclusively available for Spring Boot projects.

Maven Compiler Plugin with source and target

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

This method sets the source and target JDK versions explicitly.

Maven Compiler Plugin with release

<properties>
    <maven.compiler.release>9</maven.compiler.release>
</properties>

This method specifies the release argument, which sets the JDK version uniformly for source, target, and bootstrap options.

Differences between Properties and Compiler Plugin

1. Source and Target:

• The maven-compiler-plugin and maven.compiler.source/maven.compiler.target properties produce equivalent results.

2. Default Values:

• Both methods set default source and target versions based on the Maven compiler plugin version.

3. Java Version Compatibility:

• The specified Java version should not exceed the version of the JDK referenced by JAVA_HOME.

4. Compiler Plugin Invocation:

• Maven automatically includes the Maven compiler plugin for compilation, even if not explicitly declared in the pom.xml.

Which Way to Use?

For Java 8 and Below:

Use either maven.compiler.source/maven.compiler.target properties or the Maven compiler plugin.

From Java 9 and Above:

Consider using the release argument if you want to set a single version for source, target, and bootstrap.

Cross-Compilation Options

If the JDK referenced by JAVA_HOME is incompatible with the specified Java versions, you can explicitly provide a compatible compiler version and executable:

<configuration>
    <source>1.8</source>
    <target>1.8</target>
    <compilerVersion>1.8</compilerVersion>      
    <fork>true</fork>
    <executable>D:\jdk1.8\bin\javac</executable>                
</configuration>

Conclusion

The choice of method depends on the specific requirements and project setup. Each method provides different options for specifying Java version and handling cross-compilation scenarios. However, it is important to ensure compatibility between the specified version and the installed JDK for successful compilation.

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