Gradle:

- always use Java toolchains
- default is Java 11 (but source/targetCompatibility is still 1.8)
- use system property `toolchain` (e.g. `-Dtoolchain=25`) to compile with other Java versions

preparation for Gradle 9.x, which requires Java 17+ to run

.github/workflows/ci.yml

@@ -36,6 +36,7 @@ jobs:
           cache: gradle
 
       - name: Check with Error Prone
+        if: github.repository == 'JFormDesigner/FlatLaf'
         run: ./gradlew errorprone clean
 
       - name: Build with Gradle
@@ -67,23 +68,20 @@ jobs:
           - 8
           - 17  # LTS
           - 21  # LTS
-        toolchain: [""]
-        include:
-          - java: 21
-            toolchain: 25  # LTS
+          - 25  # LTS
 
     steps:
       - uses: actions/checkout@v4
 
-      - name: Setup Java ${{ matrix.java }}
+      - name: Setup Java 11
         uses: actions/setup-java@v4
         with:
-          java-version: ${{ matrix.java }}
-          distribution: temurin  # Java 8, 11, 17 and 21 are pre-installed on ubuntu-latest
+          java-version: 11
+          distribution: temurin  # pre-installed on ubuntu-latest
           cache: gradle
 
       - name: Build with Gradle
-        run: ./gradlew build -Dtoolchain=${{ matrix.toolchain }}
+        run: ./gradlew build -Dtoolchain=${{ matrix.java }}
 
 
   snapshot:

build.gradle.kts

@@ -43,9 +43,7 @@ println( "----------------------------------------------------------------------
 println( "FlatLaf Version: ${version}" )
 println( "Gradle ${gradle.gradleVersion} at ${gradle.gradleHomeDir}" )
 println( "Java ${System.getProperty( "java.version" )}" )
-val toolchainJavaVersion = System.getProperty( "toolchain" )
-if( !toolchainJavaVersion.isNullOrEmpty() )
-	println( "Java toolchain ${toolchainJavaVersion}" )
+println( "Java toolchain ${System.getProperty( "toolchain", "11" )}" )
 println()
 
 

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

@@ -18,7 +18,7 @@ plugins {
 	java
 }
 
-if( JavaVersion.current() >= JavaVersion.VERSION_1_9 ) {
+if( java.toolchain.languageVersion.get().asInt() >= 9 ) {
 	sourceSets {
 		create( "java9" ) {
 			java {

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

@@ -29,7 +29,7 @@ plugins {
 	java
 }
 
-if( JavaVersion.current() >= JavaVersion.VERSION_1_9 ) {
+if( java.toolchain.languageVersion.get().asInt() >= 9 ) {
 	sourceSets {
 		create( "module-info" ) {
 			java {

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

@@ -18,9 +18,6 @@ plugins {
 	java
 }
 
-val toolchainJavaVersion = System.getProperty( "toolchain" )
-if( !toolchainJavaVersion.isNullOrEmpty() ) {
-	java.toolchain {
-		languageVersion = JavaLanguageVersion.of( toolchainJavaVersion )
-	}
+java.toolchain {
+	languageVersion = JavaLanguageVersion.of( System.getProperty( "toolchain", "11" ) )
 }

flatlaf-core/build.gradle.kts

@@ -90,7 +90,7 @@ tasks {
 		useJUnitPlatform()
 		testLogging.exceptionFormat = org.gradle.api.tasks.testing.logging.TestExceptionFormat.FULL
 
-		if( JavaVersion.current() >= JavaVersion.VERSION_1_9 )
+		if( java.toolchain.languageVersion.get().asInt() >= 9 )
 			jvmArgs( listOf( "--add-opens", "java.desktop/javax.swing.plaf.basic=ALL-UNNAMED" ) )
 	}
 

flatlaf-demo/build.gradle.kts

@@ -46,7 +46,7 @@ tasks {
 		manifest {
 			attributes( "Main-Class" to "com.formdev.flatlaf.demo.FlatLafDemo" )
 
-			if( JavaVersion.current() >= JavaVersion.VERSION_1_9 )
+			if( java.toolchain.languageVersion.get().asInt() >= 9 )
 				attributes( "Multi-Release" to "true" )
 
 			// allow loading FlatLaf native library in Java 24+ (see https://openjdk.org/jeps/472)

flatlaf-fonts/flatlaf-fonts-inter/build.gradle.kts

@@ -26,6 +26,7 @@ if( !rootProject.hasProperty( "release" ) )
 
 plugins {
 	`java-library`
+	`flatlaf-toolchain`
 	`flatlaf-module-info`
 	`flatlaf-publish`
 }

flatlaf-fonts/flatlaf-fonts-jetbrains-mono/build.gradle.kts

@@ -26,6 +26,7 @@ if( !rootProject.hasProperty( "release" ) )
 
 plugins {
 	`java-library`
+	`flatlaf-toolchain`
 	`flatlaf-module-info`
 	`flatlaf-publish`
 }

flatlaf-fonts/flatlaf-fonts-roboto-mono/build.gradle.kts

@@ -26,6 +26,7 @@ if( !rootProject.hasProperty( "release" ) )
 
 plugins {
 	`java-library`
+	`flatlaf-toolchain`
 	`flatlaf-module-info`
 	`flatlaf-publish`
 }

flatlaf-fonts/flatlaf-fonts-roboto/build.gradle.kts

@@ -26,6 +26,7 @@ if( !rootProject.hasProperty( "release" ) )
 
 plugins {
 	`java-library`
+	`flatlaf-toolchain`
 	`flatlaf-module-info`
 	`flatlaf-publish`
 }

flatlaf-testing/flatlaf-testing-modular-app/build.gradle.kts

@@ -16,6 +16,7 @@
 
 plugins {
 	`java-library`
+	`flatlaf-toolchain`
 	`flatlaf-module-info`
 }
 

flatlaf-theme-editor/build.gradle.kts

@@ -44,7 +44,7 @@ tasks {
 		manifest {
 			attributes( "Main-Class" to "com.formdev.flatlaf.themeeditor.FlatLafThemeEditor" )
 
-			if( JavaVersion.current() >= JavaVersion.VERSION_1_9 )
+			if( java.toolchain.languageVersion.get().asInt() >= 9 )
 				attributes( "Multi-Release" to "true" )
 
 			// allow loading FlatLaf native library in Java 24+ (see https://openjdk.org/jeps/472)