support loading FlatLaf properties files from named Java modules without the need to open that package in module-info.java (issue #1026)

CHANGELOG.md

@@ -3,6 +3,13 @@ FlatLaf Change Log
 
 ## 3.7-SNAPSHOT
 
+#### New features and improvements
+
+- If using `FlatLaf.registerCustomDefaultsSource( "com.myapp.themes" )` and
+  named Java modules, it is no longer necessary to add `opens com.myapp.themes;`
+  to `module-info.java`. (issue #1026)
+
+
 #### Fixed bugs
 
 - Tree and List: Fixed painting of rounded drop backgrounds. (issue #1023)

flatlaf-core/src/main/java/com/formdev/flatlaf/FlatLaf.java

@@ -911,8 +911,7 @@ public abstract class FlatLaf
 	 * <p>
 	 * Invoke this method before setting the look and feel.
 	 * <p>
-	 * If using Java modules, the package must be opened in {@code module-info.java}.
+	 * If using Java modules, it is not necessary to open the package in {@code module-info.java}.
-	 * Otherwise, use {@link #registerCustomDefaultsSource(URL)}.
 	 *
 	 * @param packageName a package name (e.g. "com.myapp.resources")
 	 */
@@ -959,9 +958,9 @@ public abstract class FlatLaf
 	 * <p>
 	 * See {@link #registerCustomDefaultsSource(String)} for details.
 	 * <p>
-	 * This method is useful if using Java modules and the package containing the properties files
-	 * is not opened in {@code module-info.java}.
 	 * E.g. {@code FlatLaf.registerCustomDefaultsSource( MyApp.class.getResource( "/com/myapp/themes/" ) )}.
+	 * <p>
+	 * If using Java modules, it is not necessary to open the package in {@code module-info.java}.
 	 *
 	 * @param packageUrl a package URL
 	 * @since 2

flatlaf-core/src/main/java/com/formdev/flatlaf/UIDefaultsLoader.java

@@ -205,20 +205,37 @@ class UIDefaultsLoader
 					if( classLoader != null && !addonClassLoaders.contains( classLoader ) )
 						addonClassLoaders.add( classLoader );
 
-					packageName = packageName.replace( '.', '/' );
 					if( classLoader == null )
 						classLoader = FlatLaf.class.getClassLoader();
 
+					// Get package URL using ClassLoader.getResource(...) because this works
+					// also in named Java modules, even without opening the package in module-info.java.
+					// This extra step is necessary because ClassLoader.getResource("<package>/<file>.properties")
+					// does not work for named Java modules.
+					URL url = classLoader.getResource( packageName.replace( '.', '/' ) );
+					if( url == null ) {
+						LoggingFacade.INSTANCE.logSevere( "FlatLaf: Failed to find package '"
+							+ packageName + "' to load properties files.", null );
+						continue;
+					}
+					String packageUrl = url.toExternalForm();
+					if( !packageUrl.endsWith( "/" ) )
+						packageUrl = packageUrl.concat( "/" );
+
 					for( Class<?> lafClass : lafClasses ) {
-						String propertiesName = packageName + '/' + simpleClassName( lafClass ) + ".properties";
+						URL propertiesUrl = new URL( packageUrl + simpleClassName( lafClass ) + ".properties" );
-						try( InputStream in = classLoader.getResourceAsStream( propertiesName ) ) {
+
-							if( in != null )
+						try( InputStream in = propertiesUrl.openStream() ) {
 							properties.load( in );
+						} catch( FileNotFoundException ex ) {
+							// ignore
 						}
 					}
 				} else if( source instanceof URL ) {
 					// load from package URL
-					URL packageUrl = (URL) source;
+					String packageUrl = ((URL)source).toExternalForm();
+					if( !packageUrl.endsWith( "/" ) )
+						packageUrl = packageUrl.concat( "/" );
 					for( Class<?> lafClass : lafClasses ) {
 						URL propertiesUrl = new URL( packageUrl + simpleClassName( lafClass ) + ".properties" );
 

flatlaf-testing/flatlaf-testing-modular-app/FlatModularAppTest JAR.launch

@@ -7,6 +7,8 @@
     <listAttribute key="org.eclipse.debug.core.MAPPED_RESOURCE_TYPES">
         <listEntry value="4"/>
     </listAttribute>
+    <stringAttribute key="org.eclipse.debug.core.source_locator_id" value="org.eclipse.jdt.launching.sourceLocator.JavaSourceLookupDirector"/>
+    <stringAttribute key="org.eclipse.debug.core.source_locator_memento" value="&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot; standalone=&quot;no&quot;?&gt;&#13;&#10;&lt;sourceLookupDirector&gt;&#13;&#10;    &lt;sourceContainers duplicates=&quot;false&quot;&gt;&#13;&#10;        &lt;container memento=&quot;&amp;lt;?xml version=&amp;quot;1.0&amp;quot; encoding=&amp;quot;UTF-8&amp;quot; standalone=&amp;quot;no&amp;quot;?&amp;gt;&amp;#13;&amp;#10;&amp;lt;javaProject name=&amp;quot;flatlaf-core&amp;quot;/&amp;gt;&amp;#13;&amp;#10;&quot; typeId=&quot;org.eclipse.jdt.launching.sourceContainer.javaProject&quot;/&gt;&#13;&#10;        &lt;container memento=&quot;&amp;lt;?xml version=&amp;quot;1.0&amp;quot; encoding=&amp;quot;UTF-8&amp;quot; standalone=&amp;quot;no&amp;quot;?&amp;gt;&amp;#13;&amp;#10;&amp;lt;javaProject name=&amp;quot;flatlaf-testing-modular-app&amp;quot;/&amp;gt;&amp;#13;&amp;#10;&quot; typeId=&quot;org.eclipse.jdt.launching.sourceContainer.javaProject&quot;/&gt;&#13;&#10;    &lt;/sourceContainers&gt;&#13;&#10;&lt;/sourceLookupDirector&gt;&#13;&#10;"/>
     <booleanAttribute key="org.eclipse.jdt.launching.ATTR_ATTR_USE_ARGFILE" value="false"/>
     <booleanAttribute key="org.eclipse.jdt.launching.ATTR_EXCLUDE_TEST_CODE" value="true"/>
     <booleanAttribute key="org.eclipse.jdt.launching.ATTR_SHOW_CODEDETAILS_IN_EXCEPTION_MESSAGES" value="true"/>
@@ -17,11 +19,11 @@
     <stringAttribute key="org.eclipse.jdt.launching.MAIN_TYPE" value="-Ddummy=dummy"/>
     <listAttribute key="org.eclipse.jdt.launching.MODULEPATH">
         <listEntry value="&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot; standalone=&quot;no&quot;?&gt;&#13;&#10;&lt;runtimeClasspathEntry containerPath=&quot;org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/jdk-17/&quot; path=&quot;4&quot; type=&quot;4&quot;/&gt;&#13;&#10;"/>
-        <listEntry value="&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot; standalone=&quot;no&quot;?&gt;&#13;&#10;&lt;runtimeClasspathEntry internalArchive=&quot;/flatlaf-testing-modular-app/build/libs/flatlaf-testing-modular-app-3.0-SNAPSHOT.jar&quot; path=&quot;4&quot; type=&quot;2&quot;/&gt;&#13;&#10;"/>
+        <listEntry value="&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot; standalone=&quot;no&quot;?&gt;&#13;&#10;&lt;runtimeClasspathEntry internalArchive=&quot;/flatlaf-testing-modular-app/run/flatlaf-testing-modular-app-999-SNAPSHOT.jar&quot; path=&quot;4&quot; type=&quot;2&quot;/&gt;&#13;&#10;"/>
-        <listEntry value="&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot; standalone=&quot;no&quot;?&gt;&#13;&#10;&lt;runtimeClasspathEntry internalArchive=&quot;/flatlaf-core/build/libs/flatlaf-3.0-SNAPSHOT.jar&quot; path=&quot;4&quot; type=&quot;2&quot;/&gt;&#13;&#10;"/>
+        <listEntry value="&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot; standalone=&quot;no&quot;?&gt;&#13;&#10;&lt;runtimeClasspathEntry internalArchive=&quot;/flatlaf-testing-modular-app/run/flatlaf-999-SNAPSHOT.jar&quot; path=&quot;4&quot; type=&quot;2&quot;/&gt;&#13;&#10;"/>
-        <listEntry value="&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot; standalone=&quot;no&quot;?&gt;&#13;&#10;&lt;runtimeClasspathEntry internalArchive=&quot;/flatlaf-extras/build/libs/flatlaf-extras-3.0-SNAPSHOT.jar&quot; path=&quot;4&quot; type=&quot;2&quot;/&gt;&#13;&#10;"/>
+        <listEntry value="&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot; standalone=&quot;no&quot;?&gt;&#13;&#10;&lt;runtimeClasspathEntry internalArchive=&quot;/flatlaf-testing-modular-app/run/flatlaf-extras-999-SNAPSHOT.jar&quot; path=&quot;4&quot; type=&quot;2&quot;/&gt;&#13;&#10;"/>
-        <listEntry value="&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot; standalone=&quot;no&quot;?&gt;&#13;&#10;&lt;runtimeClasspathEntry internalArchive=&quot;/flatlaf-fonts-inter/build/libs/flatlaf-fonts-inter-3.19-SNAPSHOT.jar&quot; path=&quot;4&quot; type=&quot;2&quot;/&gt;&#13;&#10;"/>
+        <listEntry value="&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot; standalone=&quot;no&quot;?&gt;&#13;&#10;&lt;runtimeClasspathEntry internalArchive=&quot;/flatlaf-testing-modular-app/run/flatlaf-fonts-inter-999-SNAPSHOT.jar&quot; path=&quot;4&quot; type=&quot;2&quot;/&gt;&#13;&#10;"/>
-        <listEntry value="&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot; standalone=&quot;no&quot;?&gt;&#13;&#10;&lt;runtimeClasspathEntry externalArchive=&quot;C:/Users/charly/.gradle/caches/modules-2/files-2.1/com.formdev/svgSalamander/1.1.4/e61742cb8baaf9ecf57a9779763d1de21ca9db5a/svgSalamander-1.1.4.jar&quot; path=&quot;4&quot; type=&quot;2&quot;/&gt;&#13;&#10;"/>
+        <listEntry value="&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot; standalone=&quot;no&quot;?&gt;&#13;&#10;&lt;runtimeClasspathEntry internalArchive=&quot;/flatlaf-testing-modular-app/run/jsvg-999.jar&quot; path=&quot;4&quot; type=&quot;2&quot;/&gt;&#13;&#10;"/>
     </listAttribute>
     <stringAttribute key="org.eclipse.jdt.launching.MODULE_NAME" value="flatlaf-testing-modular-app"/>
     <stringAttribute key="org.eclipse.jdt.launching.PROGRAM_ARGUMENTS" value="-m com.formdev.flatlaf.testing.modular.app/com.formdev.flatlaf.testing.modular.app.FlatModularAppTest"/>

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

@@ -30,3 +30,20 @@ flatlafModuleInfo {
 	dependsOn( ":flatlaf-extras:jar" )
 	dependsOn( ":flatlaf-fonts-inter:jar" )
 }
+
+tasks {
+	register( "build-for-debugging" ) {
+		group = "build"
+
+		dependsOn( "build" )
+
+		doLast {
+			copy {
+				from( project.tasks["jar"].outputs )
+				from( configurations.runtimeClasspath )
+				into( "run" )
+				rename( "-[0-9][0-9.]*[0-9]", "-999" )
+			}
+		}
+	}
+}

flatlaf-testing/flatlaf-testing-modular-app/src/main/java/com/formdev/flatlaf/testing/modular/app/FlatModularAppTest.java

@@ -38,8 +38,12 @@ public class FlatModularAppTest
 		SwingUtilities.invokeLater( () -> {
 			FlatInterFont.installBasic();
 
+			FlatLaf.registerCustomDefaultsSource( "com.formdev.flatlaf.testing.modular.app.themes" );
+			FlatLaf.registerCustomDefaultsSource( "com.formdev.flatlaf.testing.modular.app.themes2",
+				FlatModularAppTest.class.getClassLoader() );
 			FlatLaf.registerCustomDefaultsSource(
-				FlatModularAppTest.class.getResource( "/com/formdev/flatlaf/testing/modular/app/themes/" ) );
+				FlatModularAppTest.class.getResource( "/com/formdev/flatlaf/testing/modular/app/themes3" ) );
+
 			FlatLightLaf.setup();
 
 			JButton button1 = new JButton( "Hello" );

flatlaf-testing/flatlaf-testing-modular-app/src/main/resources/com/formdev/flatlaf/testing/modular/app/themes/FlatLightLaf.properties

@@ -14,7 +14,4 @@
 # limitations under the License.
 #
 
-@background = #fff
 @foreground = #f00
-
-ButtonUI = com.formdev.flatlaf.testing.modular.app.plaf.MyButtonUI

flatlaf-testing/flatlaf-testing-modular-app/src/main/resources/com/formdev/flatlaf/testing/modular/app/themes2/FlatLightLaf.properties

@@ -0,0 +1,17 @@
+#
+# Copyright 2025 FormDev Software GmbH
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+@background = #efe

flatlaf-testing/flatlaf-testing-modular-app/src/main/resources/com/formdev/flatlaf/testing/modular/app/themes3/FlatLightLaf.properties

@@ -0,0 +1,17 @@
+#
+# Copyright 2025 FormDev Software GmbH
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+ButtonUI = com.formdev.flatlaf.testing.modular.app.plaf.MyButtonUI