NoClassDefFoundError of com/fasterxml/jackson/databind/ObjectMapper with Maven

fasterxml, jackson, java, maven

Solution

As I answered here

The default maven plugin doesn't build a fat jar with dependencies.

To build a jar bundled with its dependencies so that we can execute it with `java -jar`, we can use maven-assembly-plugin, which packages the jar with the name `xxx-jar-with-dependencies.jar`.

Here is a sample `pom.xml`

<build>
    <plugins>
        <plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <version>3.0.0</version>
            <configuration>
                <descriptorRefs>
                    <descriptorRef>jar-with-dependencies</descriptorRef>
                </descriptorRefs>
                <archive>
                    <manifest>
                        <mainClass>com.example.yourMain</mainClass>
                    </manifest>
                </archive>
            </configuration>
            <executions>
                <execution>
                    <id>make-assembly</id> <!-- this is used for inheritance merges -->
                    <phase>package</phase> <!-- bind to the packaging phase -->
                    <goals>
                        <goal>single</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Now you should be able to run your jar with

java -jar xxx-jar-with-dependencies.jar

Problem

This is a similar question as the one here, which is unfortunately unresolved yet. If you want to debug the code, here is the GitHub repo. I got the following `NoClassDefFoundError` for `ObjectMapper` though I have added the related dependency to Mave `pom.xml`. ``` Exception in thread "main" java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/ObjectMapper at demo.DemoMain.main(DemoMain.java:10) Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.databind.ObjectMapper 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) ... 1 more ``` Here is the source code `DemoMain.java` ``` package demo; import com.fasterxml.jackson.databind.ObjectMapper; public class DemoMain { public static void main(String[] args) { System.out.println("Start"); ObjectMapper mapper = new ObjectMapper(); System.out.println("End"); } } ``` This is my `pom.xml` ``` <?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/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.example</groupId> <artifactId>Demo</artifactId> <version>1.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>2.8.3</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>2.8.3</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.8.3</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> <version>3.0.0</version> <configuration> <archive> <index>true</index> <manifest> <addClasspath>true</addClasspath> <mainClass>demo.DemoMain</mainClass> </manifest> </archive> </configuration> </plugin> </plugins> </build> ``` I compile and run the app by ``` mvn clean install java -jar target/Demo-1.0-SNAPSHOT.jar ```

Original source

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