Kotlin Jackson module: ClassNotFoundException: kotlin.jvm.internal.KotlinClass

Libraries
1

I am trying to use the Kotlin Jackson module to deserialize some JSON:

import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper

data class IntegerWrapper(val value: Int)

fun main(args: Array<String>) {

    val mapper = jacksonObjectMapper()
    val json = """{"value": "42"}"""
    val wrapper = mapper.readValue(json, IntegerWrapper::class.java)
    println("Wrapper: $wrapper")

}

pom.xml:

    <dependencies>
        <!-- This has a transitive dependency to kotlin-runtime -->
        <!-- kotlin-runtime is on the compile and runtime classpaths -->
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-stdlib</artifactId>
            <version>1.0.0</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.module</groupId>
            <artifactId>jackson-module-kotlin</artifactId>
            <version>2.6.5-1</version>
        </dependency>
    </dependencies>

    <build>
        <sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
        <testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <version>${kotlin.version}</version>
                <executions>
                    <execution>
                        <id>compile</id>
                        <phase>compile</phase>
                        <goals>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>test-compile</id>
                        <phase>test-compile</phase>
                        <goals>
                            <goal>test-compile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

Stack trace:

Exception in thread "main" java.lang.NoClassDefFoundError: kotlin/jvm/internal/KotlinClass
    at com.fasterxml.jackson.module.kotlin.KotlinNamesAnnotationIntrospector.findKotlinParameterName(KotlinModule.kt:99)
    at com.fasterxml.jackson.module.kotlin.KotlinNamesAnnotationIntrospector.findImplicitPropertyName(KotlinModule.kt:57)
    at com.fasterxml.jackson.databind.introspect.AnnotationIntrospectorPair.findImplicitPropertyName(AnnotationIntrospectorPair.java:467)
    at com.fasterxml.jackson.databind.introspect.POJOPropertiesCollector._addCreatorParam(POJOPropertiesCollector.java:436)
    at com.fasterxml.jackson.databind.introspect.POJOPropertiesCollector._addCreators(POJOPropertiesCollector.java:415)
    at com.fasterxml.jackson.databind.introspect.POJOPropertiesCollector.collectAll(POJOPropertiesCollector.java:285)
    at com.fasterxml.jackson.databind.introspect.POJOPropertiesCollector.getPropertyMap(POJOPropertiesCollector.java:248)
    at com.fasterxml.jackson.databind.introspect.POJOPropertiesCollector.getProperties(POJOPropertiesCollector.java:155)
    at com.fasterxml.jackson.databind.introspect.BasicBeanDescription._properties(BasicBeanDescription.java:142)
    at com.fasterxml.jackson.databind.introspect.BasicBeanDescription.findProperties(BasicBeanDescription.java:217)
    at com.fasterxml.jackson.databind.deser.BasicDeserializerFactory._findCreatorsFromProperties(BasicDeserializerFactory.java:333)
    at com.fasterxml.jackson.databind.deser.BasicDeserializerFactory._constructDefaultValueInstantiator(BasicDeserializerFactory.java:315)
    at com.fasterxml.jackson.databind.deser.BasicDeserializerFactory.findValueInstantiator(BasicDeserializerFactory.java:254)
    at com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.buildBeanDeserializer(BeanDeserializerFactory.java:222)
    at com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.createBeanDeserializer(BeanDeserializerFactory.java:142)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer2(DeserializerCache.java:403)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer(DeserializerCache.java:352)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCache2(DeserializerCache.java:264)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCacheValueDeserializer(DeserializerCache.java:244)
    at com.fasterxml.jackson.databind.deser.DeserializerCache.findValueDeserializer(DeserializerCache.java:142)
    at com.fasterxml.jackson.databind.DeserializationContext.findRootValueDeserializer(DeserializationContext.java:461)
    at com.fasterxml.jackson.databind.ObjectMapper._findRootDeserializer(ObjectMapper.java:3838)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3732)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2726)
    at demo.DemoKt.main(Demo.kt:11)
Caused by: java.lang.ClassNotFoundException: kotlin.jvm.internal.KotlinClass
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 25 more

I get this exception in IntelliJ IDEA, Eclipse, and command line. As far as I know my plugins are up-to-date (I installed them yesterday or today). Does anybody have a hint or suggestion? I didn’t find this exact problem using my search skills.

Links:

2

Looks like this version of jackson-module-kotlin hasn’t been compiled against Kotlin 1.0. Try with the latest version.

1 Like
3

Thank you. Updating the dependency fixed it.

<dependency>
    <groupId>com.fasterxml.jackson.module</groupId>
    <artifactId>jackson-module-kotlin</artifactId>
    <version>2.6.5-2</version>
</dependency>

Since the latest version is not yet on Maven central, I needed to add a repository:

<repositories>
    <!-- Remove this once jackson-module-kotlin:2.6.5-2 is on central -->
    <repository>
        <id>jaysonminard-kohesive</id>
        <url>http://dl.bintray.com/jaysonminard/kohesive</url>
    </repository>
</repositories>

This approach was already explained in the GitHub link above. D’oh! I thought I had tried it.