Spotless formats code differently between JDK versions (17 vs 21)

We've seen cases in the Jenkins project use of spotless formatting where a comment adjacent to a case statement inside a switch will be formatted on Java 17 with a different indentation than on Java 21, even though the Java version is declared as Java 17 in the Maven project using Spotless.

A recent example is:

Bump org.jenkins-ci:jenkins from 1.131 to 1.132 jenkinsci/winstone#436

When we move the comment so that it is either inside the case or outside the switch, then the Java version dependent formatting does not happen.

I'm sure this bug is real, but it is almost definitely a bug in the formatter you are using in Spotless, rather than in Spotless itself. So either googleJavaFormat or eclipse, depending on which one you are using.

When we move the comment so that it is either inside the case or outside the switch, then the platform dependent formatting does not happen.

That is a useful and actionable bug report for whichever formatter you are using through Spotless.

@nedtwigg

@nedtwigg I think the problem is in Spotless itself; see #2447 (comment).

Adapt code comments to spotless dependency on Java version

my summary of that comment

yes, if you don't specify a version for a formatter, Spotless picks the latest available which will run on the JVM you are using
if you want the same behavior on development environments running on multiple JRE versions, you will need to set the version explicitly
looking at the source-level of the project for JVM_SUPPORT calculations is a neat idea, but plumbing that out would be a significant task. I'm open to a PR which adds it, but I bet just pinning a specific version is going to way more bang for your buck

Revert "Bump org.jenkins-ci:jenkins from 1.131 to 1.132 (jenkinsci#436)"

Declare formatter version to avoid spotless choosing a version

Use spotless / palantirJavaFormat - 2.56.0 for all JDKs

Hints in case I or someone else finds the time to fix this:

spotless/lib/src/main/java/com/diffplug/spotless/Jvm.java

Lines 36 to 52 in 2d32ccd

    
           private static final int VERSION; 
        
           static { 
        
           	String jre = System.getProperty("java.version"); 
        
           	if (jre.startsWith("1.8")) { 
        
           		VERSION = 8; 
        
           	} else { 
        
           		Matcher matcher = Pattern.compile("(\\d+)").matcher(jre); 
        
           		if (!matcher.find()) { 
        
           			throw new IllegalArgumentException("Expected " + jre + " to start with an integer"); 
        
           		} 
        
           		VERSION = Integer.parseInt(matcher.group(1)); 
        
           		if (VERSION <= 8) { 
        
           			throw new IllegalArgumentException("Expected " + jre + " to start with an integer greater than 8"); 
        
           		} 
        
           	} 
        
           }

is the problem (this code should really not exist), and specifically

spotless/lib/src/main/java/com/diffplug/spotless/Jvm.java

Lines 122 to 127 in 2d32ccd

    
           /** @return Highest formatter version recommended for this JVM (null, if JVM not supported) */ 
        
           @Nullable 
        
           public V getRecommendedFormatterVersion() { 
        
           	Integer configuredJvmVersionOrNull = jvm2fmtMaxVersion.floorKey(Jvm.version()); 
        
           	return (null == configuredJvmVersionOrNull) ? null : jvm2fmtMaxVersion.get(configuredJvmVersionOrNull); 
        
           }

spotless/lib/src/main/java/com/diffplug/spotless/java/PalantirJavaFormatStep.java

Line 32 in 2d32ccd

    
           private static final Jvm.Support<String> JVM_SUPPORT = Jvm.<String> support(NAME).add(8, "1.1.0").add(11, "2.28.0").add(21, "2.57.0");

spotless/plugin-maven/src/main/java/com/diffplug/spotless/maven/java/PalantirJavaFormat.java

Line 38 in 2d32ccd

    
           String version = this.version != null ? this.version : PalantirJavaFormatStep.defaultVersion();

needs to inspect the mojo configuration for https://maven.apache.org/plugins/maven-compiler-plugin/compile-mojo.html#release falling back to https://maven.apache.org/plugins/maven-compiler-plugin/compile-mojo.html#source and finally falling back to the historical default of JDK 5.

(Ideally the source level for src/test/java/ would be calculated independently, in case it is using a newer version than src/main/java/, but I suppose the mojo does not understand how to run two formatters on the same module.)

Declare formatter version to avoid spotless choosing a version (#681)

Declare formatter version to avoid spotless choosing a version (#1151)

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Spotless formats code differently between JDK versions (17 vs 21) #2503

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	private static final int VERSION;

	static {
	String jre = System.getProperty("java.version");
	if (jre.startsWith("1.8")) {
	VERSION = 8;
	} else {
	Matcher matcher = Pattern.compile("(\\d+)").matcher(jre);
	if (!matcher.find()) {
	throw new IllegalArgumentException("Expected " + jre + " to start with an integer");
	}
	VERSION = Integer.parseInt(matcher.group(1));
	if (VERSION <= 8) {
	throw new IllegalArgumentException("Expected " + jre + " to start with an integer greater than 8");
	}
	}
	}

	/** @return Highest formatter version recommended for this JVM (null, if JVM not supported) */
	@Nullable
	public V getRecommendedFormatterVersion() {
	Integer configuredJvmVersionOrNull = jvm2fmtMaxVersion.floorKey(Jvm.version());
	return (null == configuredJvmVersionOrNull) ? null : jvm2fmtMaxVersion.get(configuredJvmVersionOrNull);
	}

Spotless formats code differently between JDK versions (17 vs 21) #2503

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nedtwigg commented on Jun 3, 2025

basil commented on Jun 3, 2025

nedtwigg commented on Jun 7, 2025

jglick commented on Jun 26, 2025

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