Vaadin 24.4.13 Prepare-frontend fails if I using a @Theme annotation

Flow
1

Hi I’m building application with Vaadin 24. When I try to using my theme by adding a Theme annotation to my ApplicationServlet which extends VaadinServlet, production building fails in prepare-frontend.

Could not execute prepare-frontend goal.: Error occured during goal execution: Cannot invoke "java.lang.Class.isInterface()" because the return value of "org.reflections.Reflections.forClass(String, java.lang.ClassLoader[])" is null

My debug console output

java.lang.NoClassDefFoundError: jakarta/servlet/http/HttpServlet
    at java.lang.ClassLoader.defineClass1 (Native Method)
    at java.lang.ClassLoader.defineClass (ClassLoader.java:1017)
    at java.security.SecureClassLoader.defineClass (SecureClassLoader.java:150)
    at java.net.URLClassLoader.defineClass (URLClassLoader.java:524)
    at java.net.URLClassLoader$1.run (URLClassLoader.java:427)
    at java.net.URLClassLoader$1.run (URLClassLoader.java:421)
    at java.security.AccessController.doPrivileged (AccessController.java:712)
    at java.net.URLClassLoader.findClass (URLClassLoader.java:420)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.findClassInternal (ClassRealm.java:256)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClassFromSelf (ClassRealm.java:351)
    at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass (SelfFirstStrategy.java:36)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass (ClassRealm.java:225)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass (ClassRealm.java:210)
    at java.lang.ClassLoader.loadClass (ClassLoader.java:579)
    at java.lang.ClassLoader.loadClass (ClassLoader.java:525)
    at java.lang.ClassLoader.defineClass1 (Native Method)
    at java.lang.ClassLoader.defineClass (ClassLoader.java:1017)
    at java.security.SecureClassLoader.defineClass (SecureClassLoader.java:150)
    at java.net.URLClassLoader.defineClass (URLClassLoader.java:524)
    at java.net.URLClassLoader$1.run (URLClassLoader.java:427)
    at java.net.URLClassLoader$1.run (URLClassLoader.java:421)
    at java.security.AccessController.doPrivileged (AccessController.java:712)
    at java.net.URLClassLoader.findClass (URLClassLoader.java:420)
    at java.lang.ClassLoader.loadClass (ClassLoader.java:592)
    at java.lang.ClassLoader.loadClass (ClassLoader.java:525)
    at com.vaadin.flow.server.scanner.ReflectionsClassFinder$LoggingReflections.forClass (ReflectionsClassFinder.java:172)
    at org.reflections.Reflections.lambda$getTypesAnnotatedWith$12 (Reflections.java:405)
    at java.util.stream.ReferencePipeline$2$1.accept (ReferencePipeline.java:178)
    at java.util.Iterator.forEachRemaining (Iterator.java:133)
    at java.util.Spliterators$IteratorSpliterator.forEachRemaining (Spliterators.java:1845)
    at java.util.stream.AbstractPipeline.copyInto (AbstractPipeline.java:509)
    at java.util.stream.AbstractPipeline.wrapAndCopyInto (AbstractPipeline.java:499)
    at java.util.stream.ReduceOps$ReduceOp.evaluateSequential (ReduceOps.java:921)
    at java.util.stream.AbstractPipeline.evaluate (AbstractPipeline.java:234)
    at java.util.stream.ReferencePipeline.collect (ReferencePipeline.java:682)
    at org.reflections.util.QueryFunction.lambda$filter$3 (QueryFunction.java:32)
    at org.reflections.util.QueryFunction.lambda$add$9 (QueryFunction.java:66)
    at org.reflections.util.QueryFunction.lambda$add$9 (QueryFunction.java:66)
    at org.reflections.util.QueryFunction.lambda$asClass$13 (QueryFunction.java:89)
    at org.reflections.Reflections.get (Reflections.java:365)
    at org.reflections.Reflections.getTypesAnnotatedWith (Reflections.java:403)
    at com.vaadin.flow.server.scanner.ReflectionsClassFinder.getAnnotatedClasses (ReflectionsClassFinder.java:87)
    at com.vaadin.flow.server.frontend.scanner.ClassFinder$CachedClassFinder.lambda$getAnnotatedClasses$0 (ClassFinder.java:154)
    at java.util.HashMap.computeIfAbsent (HashMap.java:1220)
    at com.vaadin.flow.server.frontend.scanner.ClassFinder$CachedClassFinder.getAnnotatedClasses (ClassFinder.java:153)
    at com.vaadin.flow.server.frontend.scanner.FullDependenciesScanner.verifyTheme (FullDependenciesScanner.java:390)
    at com.vaadin.flow.server.frontend.scanner.FullDependenciesScanner.discoverTheme (FullDependenciesScanner.java:349)
    at com.vaadin.flow.server.frontend.scanner.FullDependenciesScanner.<init> (FullDependenciesScanner.java:141)
    at com.vaadin.flow.server.frontend.scanner.FullDependenciesScanner.<init> (FullDependenciesScanner.java:94)
    at com.vaadin.flow.server.frontend.scanner.FrontendDependenciesScanner$FrontendDependenciesScannerFactory.createScanner (FrontendDependenciesScanner.java:93)
    at com.vaadin.flow.server.frontend.NodeTasks.<init> (NodeTasks.java:125)
    at com.vaadin.flow.plugin.base.BuildFrontendUtil.prepareFrontend (BuildFrontendUtil.java:172)
    at com.vaadin.flow.plugin.maven.PrepareFrontendMojo.execute (PrepareFrontendMojo.java:64)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:126)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2 (MojoExecutor.java:328)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute (MojoExecutor.java:316)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:212)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:174)
    at org.apache.maven.lifecycle.internal.MojoExecutor.access$000 (MojoExecutor.java:75)
    at org.apache.maven.lifecycle.internal.MojoExecutor$1.run (MojoExecutor.java:162)
    at org.apache.maven.plugin.DefaultMojosExecutionStrategy.execute (DefaultMojosExecutionStrategy.java:39)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:159)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:105)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:73)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:53)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:118)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:261)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:173)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:101)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:906)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:283)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:206)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:77)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:569)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:255)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:201)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:361)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:314)
Caused by: java.lang.ClassNotFoundException: jakarta.servlet.http.HttpServlet
    at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass (SelfFirstStrategy.java:42)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass (ClassRealm.java:225)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass (ClassRealm.java:210)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass (ClassRealm.java:205)
    at java.lang.ClassLoader.defineClass1 (Native Method)
    at java.lang.ClassLoader.defineClass (ClassLoader.java:1017)
    at java.security.SecureClassLoader.defineClass (SecureClassLoader.java:150)
    at java.net.URLClassLoader.defineClass (URLClassLoader.java:524)
    at java.net.URLClassLoader$1.run (URLClassLoader.java:427)
    at java.net.URLClassLoader$1.run (URLClassLoader.java:421)
    at java.security.AccessController.doPrivileged (AccessController.java:712)
    at java.net.URLClassLoader.findClass (URLClassLoader.java:420)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.findClassInternal (ClassRealm.java:256)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClassFromSelf (ClassRealm.java:351)
    at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass (SelfFirstStrategy.java:36)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass (ClassRealm.java:225)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass (ClassRealm.java:210)
    at java.lang.ClassLoader.loadClass (ClassLoader.java:579)
    at java.lang.ClassLoader.loadClass (ClassLoader.java:525)
    at java.lang.ClassLoader.defineClass1 (Native Method)
    at java.lang.ClassLoader.defineClass (ClassLoader.java:1017)
    at java.security.SecureClassLoader.defineClass (SecureClassLoader.java:150)
    at java.net.URLClassLoader.defineClass (URLClassLoader.java:524)
    at java.net.URLClassLoader$1.run (URLClassLoader.java:427)
    at java.net.URLClassLoader$1.run (URLClassLoader.java:421)
    at java.security.AccessController.doPrivileged (AccessController.java:712)
    at java.net.URLClassLoader.findClass (URLClassLoader.java:420)
    at java.lang.ClassLoader.loadClass (ClassLoader.java:592)
    at java.lang.ClassLoader.loadClass (ClassLoader.java:525)
    at com.vaadin.flow.server.scanner.ReflectionsClassFinder$LoggingReflections.forClass (ReflectionsClassFinder.java:172)
    at org.reflections.Reflections.lambda$getTypesAnnotatedWith$12 (Reflections.java:405)
    at java.util.stream.ReferencePipeline$2$1.accept (ReferencePipeline.java:178)
    at java.util.Iterator.forEachRemaining (Iterator.java:133)
    at java.util.Spliterators$IteratorSpliterator.forEachRemaining (Spliterators.java:1845)
    at java.util.stream.AbstractPipeline.copyInto (AbstractPipeline.java:509)
    at java.util.stream.AbstractPipeline.wrapAndCopyInto (AbstractPipeline.java:499)
    at java.util.stream.ReduceOps$ReduceOp.evaluateSequential (ReduceOps.java:921)
    at java.util.stream.AbstractPipeline.evaluate (AbstractPipeline.java:234)
    at java.util.stream.ReferencePipeline.collect (ReferencePipeline.java:682)
    at org.reflections.util.QueryFunction.lambda$filter$3 (QueryFunction.java:32)
    at org.reflections.util.QueryFunction.lambda$add$9 (QueryFunction.java:66)
    at org.reflections.util.QueryFunction.lambda$add$9 (QueryFunction.java:66)
    at org.reflections.util.QueryFunction.lambda$asClass$13 (QueryFunction.java:89)
    at org.reflections.Reflections.get (Reflections.java:365)
    at org.reflections.Reflections.getTypesAnnotatedWith (Reflections.java:403)
    at com.vaadin.flow.server.scanner.ReflectionsClassFinder.getAnnotatedClasses (ReflectionsClassFinder.java:87)
    at com.vaadin.flow.server.frontend.scanner.ClassFinder$CachedClassFinder.lambda$getAnnotatedClasses$0 (ClassFinder.java:154)
    at java.util.HashMap.computeIfAbsent (HashMap.java:1220)
    at com.vaadin.flow.server.frontend.scanner.ClassFinder$CachedClassFinder.getAnnotatedClasses (ClassFinder.java:153)
    at com.vaadin.flow.server.frontend.scanner.FullDependenciesScanner.verifyTheme (FullDependenciesScanner.java:390)
    at com.vaadin.flow.server.frontend.scanner.FullDependenciesScanner.discoverTheme (FullDependenciesScanner.java:349)
    at com.vaadin.flow.server.frontend.scanner.FullDependenciesScanner.<init> (FullDependenciesScanner.java:141)
    at com.vaadin.flow.server.frontend.scanner.FullDependenciesScanner.<init> (FullDependenciesScanner.java:94)
    at com.vaadin.flow.server.frontend.scanner.FrontendDependenciesScanner$FrontendDependenciesScannerFactory.createScanner (FrontendDependenciesScanner.java:93)
    at com.vaadin.flow.server.frontend.NodeTasks.<init> (NodeTasks.java:125)
    at com.vaadin.flow.plugin.base.BuildFrontendUtil.prepareFrontend (BuildFrontendUtil.java:172)
    at com.vaadin.flow.plugin.maven.PrepareFrontendMojo.execute (PrepareFrontendMojo.java:64)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:126)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2 (MojoExecutor.java:328)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute (MojoExecutor.java:316)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:212)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:174)
    at org.apache.maven.lifecycle.internal.MojoExecutor.access$000 (MojoExecutor.java:75)
    at org.apache.maven.lifecycle.internal.MojoExecutor$1.run (MojoExecutor.java:162)
    at org.apache.maven.plugin.DefaultMojosExecutionStrategy.execute (DefaultMojosExecutionStrategy.java:39)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:159)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:105)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:73)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:53)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:118)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:261)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:173)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:101)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:906)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:283)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:206)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:77)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:569)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:255)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:201)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:361)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:314)

I’m sure I have a jakarta.servlet-api 6.1.0 dependency in my pom

<dependency>
    <groupId>jakarta.servlet</groupId>
    <artifactId>jakarta.servlet-api</artifactId>
    <version>6.1.0</version>
    <scope>provided</scope>
</dependency>

Everything goes well if I remove the @Theme annotation. I also using @Push in the ApplicationServlet and works well.

2

@Theme is usually placed on a Java class that implements AppShellConfigurator.
If possible, please provide your pom.xml.
Also you can check this example project that also has the theme annotation, it doesn’t require sprcifying any servlet-api dependency, see GitHub - vaadin/skeleton-starter-flow: Default project template for Vaadin.

1 Like
3

Move your annotation to a separat class like shown in the example skeleton-starter-flow/src/main/java/org/vaadin/example/AppShell.java at v24 · vaadin/skeleton-starter-flow · GitHub

It’s a common problem when using those on classes that are more than “just” an AppShell.

2 Likes
4

Hi @mikhail.21

Thanks for the sample code.
I created my AppShell class and moved the annotations to it just like the sample then it worked!

My pom here. Anyway, it doesn’t matter anymore I think.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>application-templete</groupId>
	<artifactId>vaadin24-app</artifactId>
	<packaging>war</packaging>
	<version>0.0.1-SNAPSHOT</version>
	<name>app</name>

	<properties>
		<maven.compiler.source>17</maven.compiler.source>
		<maven.compiler.target>17</maven.compiler.target>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<vaadin.version>24.5.0</vaadin.version>
	</properties>

	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>com.vaadin</groupId>
				<artifactId>vaadin-bom</artifactId>
				<version>${vaadin.version}</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>

	<repositories>
	</repositories>

	<dependencies>

		<!-- https://mvnrepository.com/artifact/org.apache.commons/commons-dbcp2 -->
		<dependency>
			<groupId>org.apache.commons</groupId>
			<artifactId>commons-dbcp2</artifactId>
			<version>2.12.0</version>
		</dependency>

		<!-- https://mvnrepository.com/artifact/com.mysql/mysql-connector-j -->
		<dependency>
			<groupId>com.mysql</groupId>
			<artifactId>mysql-connector-j</artifactId>
			<version>9.0.0</version>
		</dependency>

		<!-- https://mvnrepository.com/artifact/redis.clients/jedis -->
		<dependency>
			<groupId>redis.clients</groupId>
			<artifactId>jedis</artifactId>
			<version>5.1.5</version>
		</dependency>


		<!--
		https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core -->
		<dependency>
			<groupId>com.fasterxml.jackson.core</groupId>
			<artifactId>jackson-core</artifactId>
			<version>2.17.2</version>
		</dependency>

		<!-- https://mvnrepository.com/artifact/junit/junit -->
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.12</version>
			<scope>test</scope>
		</dependency>

		<!--
		https://mvnrepository.com/artifact/jakarta.servlet/jakarta.servlet-api -->
		<dependency>
			<groupId>jakarta.servlet</groupId>
			<artifactId>jakarta.servlet-api</artifactId>
			<version>6.1.0</version>
			<scope>provided</scope>
		</dependency>


		<!-- https://mvnrepository.com/artifact/com.vaadin/vaadin -->
		<dependency>
			<groupId>com.vaadin</groupId>
			<artifactId>vaadin</artifactId>
			<version>${vaadin.version}</version>
		</dependency>


	</dependencies>

	<profiles>
		<profile>
			<id>production</id>
			<build>
				<plugins>
					<plugin>
						<groupId>com.vaadin</groupId>
						<artifactId>vaadin-maven-plugin</artifactId>
						<version>${vaadin.version}</version>
						<executions>
							<execution>
								<goals>
									<goal>build-frontend</goal>
								</goals>
								<phase>compile</phase>
							</execution>
						</executions>
						<configuration>
							<!-- To always force an optimized production bundle
							build set this configuration to 'true' -->
							<!-- To possibly use the pre-compiled production
							bundle remove or set to 'false' -->
							<forceProductionBuild>true</forceProductionBuild>
							<!-- To have reproducible build by running 'npm ci' -->
							<ciBuild>true</ciBuild>
						</configuration>
					</plugin>
					<!--
                .. more plugins ..
                -->
				</plugins>
			</build>
		</profile>
	</profiles>

	<build>
		<finalName>vaadin24-app</finalName>
		<outputDirectory>${basedir}/src/main/webapp/WEB-INF/classes</outputDirectory>
		<plugins>
			<plugin>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.1</version>
				<configuration>
					<source>${maven.compiler.source}</source>
					<target>${maven.compiler.target}</target>
					<compilerArgs>
						<arg>--enable-preview</arg>
					</compilerArgs>
				</configuration>
			</plugin>

			<plugin>
				<groupId>com.vaadin</groupId>
				<artifactId>vaadin-maven-plugin</artifactId>
				<version>${vaadin.version}</version>
				<executions>
					<execution>
						<goals>
							<goal>prepare-frontend</goal>
						</goals>
					</execution>
				</executions>
			</plugin>

			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-war-plugin</artifactId>
				<version>3.3.2</version>
			</plugin>
		</plugins>
	</build>


</project>
5

Hi @knoobie

Thanks for the advice! I moved annotations to my AppShell class then it works!