Java 21 / JEP 441: Pattern Matching for switch result in com.palantir.javaformat.java.FormatterException

[matsev]

Java 21 / JEP 441 : Pattern Matching for switch code result in com.palantir.javaformat.java.FormatterException

What happened?

This method compiles using JDK 21:

class Example {
    static String test(CharSequence charSequence) {
        return switch (charSequence) {
            case String s when s.isEmpty() -> "empty string";
            case String s -> "non-empty string";
            default -> "not a String";
        };
    }
}

However, when using the spotless-maven-plugin together with <palantirJavaFormat> results in an exception:

mvn spotless:apply
[...]
Unable to format file [path to Example.java]: com.palantir.javaformat.java.FormatterException: error: expected token: 'when'; generated - instead -> [Help 1]

Maven config:

                <plugin>
                    <groupId>com.diffplug.spotless</groupId>
                    <artifactId>spotless-maven-plugin</artifactId>
                    <version>2.40.0</version>
                    <configuration>
                        <java>
                            <palantirJavaFormat>
                                <version>2.38.0</version>
                            </palantirJavaFormat>
                        </java>
                    </configuration>
                </plugin>

Maven:

mvn -v
Apache Maven 3.9.5 (57804ffe001d7215b5e7bcb531cf83df38f93546)
Java version: 21, vendor: Amazon.com Inc.
Default locale: en_GB, platform encoding: UTF-8
OS name: "mac os x", version: "13.6.1", arch: "x86_64", family: "mac"

What did you want to happen?

The maven-spotless-plugin and planter-java-format should accept or reformat code that is supported by JDK 21

[koppor]

Can you manage to compile and try #935?

[matsev]

I have checked out PR #935 locally and I manage to build it if I use JDK 17 when running Cradle.

./gradlew -v

------------------------------------------------------------
Gradle 7.6.2
------------------------------------------------------------

Build time:   2023-06-30 15:42:51 UTC
Revision:     dab132169006b16e7ada4ab2456e0c9d6415b52a

Kotlin:       1.7.10
Groovy:       3.0.13
Ant:          Apache Ant(TM) version 1.10.11 compiled on July 10 2021
JVM:          17.0.8 (Amazon.com Inc. 17.0.8+7-LTS)
OS:           Mac OS X 13.6.1 x86_64

./gradlew build
[...]
BUILD SUCCESSFUL in 29s
93 actionable tasks: 56 executed, 25 from cache, 12 up-to-date

However, that PR fails when tried to build using JDK 21 as it is not supported for running Gradle according to its compatibility matrix:

./gradlew -v

------------------------------------------------------------
Gradle 7.6.2
------------------------------------------------------------

Build time:   2023-06-30 15:42:51 UTC
Revision:     dab132169006b16e7ada4ab2456e0c9d6415b52a

Kotlin:       1.7.10
Groovy:       3.0.13
Ant:          Apache Ant(TM) version 1.10.11 compiled on July 10 2021
JVM:          21 (Amazon.com Inc. 21+35-LTS)
OS:           Mac OS X 13.6.1 x86_64

./gradlew build
[...]
FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':gradle-palantir-java-format:compileGroovy'.
> Unrecoverable compilation error: startup failed:
  General error during conversion: Unsupported class file major version 65

[mandrean]

Bump:

Java 21 is now supported from Gradle ~8.4 @matsev

[matsev]

@mandrean Thanks for the notification. I made an attempt to upgrade the Gradle wrapper to use Gradle ver 8.5, but there is some more work required to make this work, please see #977 for details