How To Enable Preview Features in Java

Post author:Noel Kamphoa
Post published:April 23, 2025
Post category:Core Java Tutorials / Java Miscellaneous

1. Introduction

Preview features in Java allow developers to experiment with new language enhancements before they are finalized. These features are fully specified and implemented, but not yet permanent parts of the Java platform. If you’re working with a Long-Term Support (LTS) version like JDK 17, you may encounter powerful additions such as pattern matching for switch, which are only accessible as preview features. In this article, you’ll learn how to enable these features in your local setup.

⚠️ Caution: Preview features are fully implemented but not finalized and should never be used in production environments.

2. Enable Preview Features via Command Line

To compile and run code that uses preview features:

🛠 Compile

javac --release 17 --enable-preview EnablePreviewFeaturesDemo.java

This will compile the class EnablePreviewFeaturesDemo in Java 17 and enable preview features. Hence, the pattern matching for switch will compile properly.

▶️ Run

java --enable-preview EnablePreviewFeaturesDemo

3. Enable Preview Features in IntelliJ IDEA

Step-by-Step

Go to File > Project Structure > Project

Set Project SDK to JDK 17
Set Language level to 17 (Preview features)

Go to File > Project Structure > Modules

Set module language level to 17 (Preview features)

Go to Run > Edit Configurations

Click Modify options (top-right)
Enable VM options
In the VM options field, add:
--enable-preview

Rebuild the project

4. Enable Preview Features in Maven

In case you have a Maven project, update the build section of the pom.xml to enable preview features.

Update your pom.xml like this:

&lt;properties>
        &lt;maven.compiler.source>17&lt;/maven.compiler.source>
        &lt;maven.compiler.target>17&lt;/maven.compiler.target>
&lt;/properties>

&lt;build>
    &lt;plugins>
       &lt;plugin>
            &lt;groupId>org.apache.maven.plugins&lt;/groupId>
            &lt;artifactId>maven-compiler-plugin&lt;/artifactId>
            &lt;configuration>
                &lt;source>${maven.compiler.source}&lt;/source>
                &lt;target>${maven.compiler.target}&lt;/target>
                &lt;compilerArgs>
                    &lt;arg>--enable-preview&lt;/arg>
                &lt;/compilerArgs>
            &lt;/configuration>
        &lt;/plugin>
        &lt;plugin>
            &lt;groupId>org.apache.maven.plugins&lt;/groupId>
            &lt;artifactId>maven-surefire-plugin&lt;/artifactId>
            &lt;version>2.22.0&lt;/version>
            &lt;configuration>
                &lt;argLine>--enable-preview&lt;/argLine>
            &lt;/configuration>
        &lt;/plugin>
    &lt;/plugins>
&lt;/build>

5. Conclusion

Preview features allow you to explore the future of Java today — but they require a bit of setup. Whether you’re compiling from the command line, working in IntelliJ, or building with Maven, enabling preview features gives you access to the latest tools and syntax enhancements.

You can find the complete code of this article here in GitHub.