Gradle:

- default is now Java 8 toolchain (to fix Eclipse project import)
- `src/main/module-info` and `src/main/java9` are compiled with Java 11 toolchain (if global toolchain is Java 8)
- `src/main/module-info` and `src/main/java9` are no longer imported into Eclipse projects
- task `errorprone` now uses at least Java 11 toolchain

.github/workflows/ci.yml

@@ -40,9 +40,9 @@ jobs:
         # - Java LTS versions (11, 17, ...)
         # - latest Java version(s)
 
-      - name: Build with Java 8
+      - name: Build with Java 11 LTS
         if: github.repository == 'JFormDesigner/FlatLaf'
-        run: ./gradlew build clean -Dtoolchain=8
+        run: ./gradlew build clean -Dtoolchain=11
 
       - name: Build with Java 17 LTS
         if: github.repository == 'JFormDesigner/FlatLaf'
@@ -57,9 +57,9 @@ jobs:
         run: ./gradlew build clean -Dtoolchain=25
 
 
-      # build with Java 11 for snapshot
+        # build with Java 8 for snapshot
 
-      - name: Build with Java 11 LTS
+      - name: Build with Java 8
         run: ./gradlew build
 
       - name: Upload artifacts to GitHub Actions

.github/workflows/error-prone.yml

@@ -34,4 +34,4 @@ jobs:
           cache: gradle
 
       - name: Check with Error Prone
-        run: ./gradlew errorprone clean
+        run: ./gradlew errorprone

build.gradle.kts

@@ -16,6 +16,8 @@
 
 import net.ltgt.gradle.errorprone.errorprone
 
+
+// initialize version
 group = "com.formdev"
 version = property( if( hasProperty( "release" ) ) "flatlaf.releaseVersion" else "flatlaf.developmentVersion" ) as String
 
@@ -24,18 +26,16 @@ val pullRequestNumber = findProperty( "github.event.pull_request.number" )
 if( pullRequestNumber != null )
 	version = "PR-${pullRequestNumber}-SNAPSHOT"
 
-
-allprojects {
+// apply version to all subprojects
+subprojects {
 	version = rootProject.version
-
-	repositories {
-		mavenCentral()
-	}
 }
 
-// check required Java version
-if( JavaVersion.current() < JavaVersion.VERSION_1_8 )
-	throw RuntimeException( "Java 8 or later required (running ${System.getProperty( "java.version" )})" )
+
+// initialize toolchain version (default is Java 8)
+val toolchainJavaVersion: String by extra {
+	System.getProperty( "toolchain", "8" )
+}
 
 // log version, Gradle and Java versions
 println()
@@ -43,7 +43,7 @@ println( "----------------------------------------------------------------------
 println( "FlatLaf Version: ${version}" )
 println( "Gradle ${gradle.gradleVersion} at ${gradle.gradleHomeDir}" )
 println( "Java ${System.getProperty( "java.version" )}" )
-println( "Java toolchain ${System.getProperty( "toolchain", "11" )}" )
+println( "Java toolchain ${toolchainJavaVersion}" )
 println()
 
 
@@ -53,6 +53,10 @@ plugins {
 }
 
 allprojects {
+	repositories {
+		mavenCentral()
+	}
+
 	tasks {
 		withType<JavaCompile>().configureEach {
 			sourceCompatibility = "1.8"
@@ -139,6 +143,15 @@ allprojects {
 						)
 					}
 				}
+
+				// Error Prone requires at lease Java 11
+				val java = (project as ExtensionAware).extensions.getByName("java") as JavaPluginExtension
+				val javaToolchains = (project as ExtensionAware).extensions.getByName("javaToolchains") as JavaToolchainService
+				if( java.toolchain.languageVersion.get().asInt() < 11 ) {
+					javaCompiler.set( javaToolchains.compilerFor {
+						languageVersion.set( JavaLanguageVersion.of( 11 ) )
+					} )
+				}
 			}
 		}
 	}

buildSrc/src/main/kotlin/flatlaf-java9.gradle.kts

@@ -18,7 +18,14 @@ plugins {
 	java
 }
 
-if( java.toolchain.languageVersion.get().asInt() >= 9 ) {
+// for Eclipse IDE project import, exclude if:
+// - plugin "eclipse" is applied; e.g. if running in Eclipse IDE with buildship plugin
+// - no taskNames specified at command line; e.g. if buildship synchronizes projects
+val exclude =
+	rootProject.plugins.hasPlugin( "eclipse" ) &&
+	gradle.startParameter.taskNames.isEmpty()
+
+if( !exclude ) {
 	sourceSets {
 		create( "java9" ) {
 			java {
@@ -35,6 +42,13 @@ if( java.toolchain.languageVersion.get().asInt() >= 9 ) {
 		named<JavaCompile>( "compileJava9Java" ) {
 			sourceCompatibility = "9"
 			targetCompatibility = "9"
+
+			// if global toolchain is Java 8, then use Java 11 to build
+			if( java.toolchain.languageVersion.get().asInt() < 9 ) {
+				javaCompiler.set( javaToolchains.compilerFor {
+					languageVersion.set( JavaLanguageVersion.of( 11 ) )
+				} )
+			}
 		}
 
 		jar {

buildSrc/src/main/kotlin/flatlaf-module-info.gradle.kts

@@ -29,7 +29,14 @@ plugins {
 	java
 }
 
-if( java.toolchain.languageVersion.get().asInt() >= 9 ) {
+// for Eclipse IDE project import, exclude if:
+// - plugin "eclipse" is applied; e.g. if running in Eclipse IDE with buildship plugin
+// - no taskNames specified at command line; e.g. if buildship synchronizes projects
+val exclude =
+	rootProject.plugins.hasPlugin( "eclipse" ) &&
+	gradle.startParameter.taskNames.isEmpty()
+
+if( !exclude ) {
 	sourceSets {
 		create( "module-info" ) {
 			java {
@@ -58,6 +65,13 @@ if( java.toolchain.languageVersion.get().asInt() >= 9 ) {
 			options.compilerArgs.add( "--module-path" )
 			options.compilerArgs.add( configurations.runtimeClasspath.get().asPath
 				+ File.pathSeparator + configurations.compileClasspath.get().asPath )
+
+			// if global toolchain is Java 8, then use Java 11 to build
+			if( java.toolchain.languageVersion.get().asInt() < 9 ) {
+				javaCompiler.set( javaToolchains.compilerFor {
+					languageVersion.set( JavaLanguageVersion.of( 11 ) )
+				} )
+			}
 		}
 
 		jar {

buildSrc/src/main/kotlin/flatlaf-toolchain.gradle.kts

@@ -18,6 +18,8 @@ plugins {
 	java
 }
 
+val toolchainJavaVersion: String by rootProject.extra
+
 java.toolchain {
-	languageVersion = JavaLanguageVersion.of( System.getProperty( "toolchain", "11" ) )
+	languageVersion = JavaLanguageVersion.of( toolchainJavaVersion )
 }

flatlaf-demo/build.gradle.kts

@@ -43,15 +43,13 @@ tasks {
 		dependsOn( ":flatlaf-intellij-themes:jar" )
 //		dependsOn( ":flatlaf-natives-jna:jar" )
 
-		manifest {
-			attributes( "Main-Class" to "com.formdev.flatlaf.demo.FlatLafDemo" )
-
-			if( java.toolchain.languageVersion.get().asInt() >= 9 )
-				attributes( "Multi-Release" to "true" )
+		manifest.attributes(
+			"Main-Class" to "com.formdev.flatlaf.demo.FlatLafDemo",
+			"Multi-Release" to "true",
 
 			// allow loading FlatLaf native library in Java 24+ (see https://openjdk.org/jeps/472)
-			attributes( "Enable-Native-Access" to "ALL-UNNAMED" )
-		}
+			"Enable-Native-Access" to "ALL-UNNAMED",
+		)
 
 		exclude( "module-info.class" )
 		exclude( "META-INF/versions/*/module-info.class" )

flatlaf-theme-editor/build.gradle.kts

@@ -41,15 +41,13 @@ tasks {
 		dependsOn( ":flatlaf-fonts-roboto:jar" )
 		dependsOn( ":flatlaf-fonts-roboto-mono:jar" )
 
-		manifest {
-			attributes( "Main-Class" to "com.formdev.flatlaf.themeeditor.FlatLafThemeEditor" )
-
-			if( java.toolchain.languageVersion.get().asInt() >= 9 )
-				attributes( "Multi-Release" to "true" )
+		manifest.attributes(
+			"Main-Class" to "com.formdev.flatlaf.themeeditor.FlatLafThemeEditor",
+			"Multi-Release" to "true",
 
 			// allow loading FlatLaf native library in Java 24+ (see https://openjdk.org/jeps/472)
-			attributes( "Enable-Native-Access" to "ALL-UNNAMED" )
-		}
+			"Enable-Native-Access" to "ALL-UNNAMED",
+		)
 
 		exclude( "module-info.class" )
 		exclude( "META-INF/versions/*/module-info.class" )