How to set Java Pattern Matching for switch in IntelliJ & Gradle

Pattern Matching for switch is a preview feature in Java 17. This post explains how to enable Pattern Matching for switch in IntelliJ IDE and Gradle build tool.

Code

public static List<GHRepository> listRepositories(GHOrganization gitHubOrganization){ 
    GitHubRepository gitHubRepository = listGitHubRepositories(gitHubOrganization); 
    switch (gitHubRepository) { 
        case GitHubRepositorySuccess gitHubRepositorySuccess -> {
            return gitHubRepositorySuccess.ghRepositories(); } 
        case GitHubRepositoryFailure gitHubRepositoryFailure -> { 
            return Collections.emptyList(); 
        } 
    } 
    return Collections.emptyList(); 
}

GitHubRepository is a java sealed interface and permits two java records that implement this interface:

In order to make the code work above, you need to enable preview view in IntelliJ & Gradle.

IntelliJ IDE

Go to File -> Project Structure -> Project.

Choose 17 (Preview) language level to make IntelliJ accept the code above.

Gradle

val ENABLE_PREVIEW = "--enable-preview" 
tasks.withType<JavaCompile>{
    options.compilerArgs.add(ENABLE_PREVIEW) 
} 
tasks.test {
    useJUnitPlatform() 
    jvmArgs(ENABLE_PREVIEW) 
}

Add the snippet above to your build.gradle.kts build descriptor file.

Use the -enable-preview java flag to run the jar:

./gradlew clean build && java --enable-preview -jar app/build/dist/app.jar -o Sealed-Classes-Kotlin-Java

Code Repository

Find the Code Repository with all the code in

• GitHub: ghb.com/Sealed-Classes-Kotlin-Java/…/java
• CodeBerg: cbg.org/…/Kotlin-Java-Sealed-Classes/…/java

Originally published at https://www.lotharschulz.info.