How to tell Maven project to include dependencies in the target folder?

Question

I am learning to use Maven. So, I have created a simple program, which just parses some JSON text. For that purpose, I have used an external library "jackson", and included it as a dependency in the pom.xml file along with dependencies required by "jackson" itself, as you can see below.

<?xml version="1.0"?>
<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>alex</groupId>
  <artifactId>test</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>
  <name>test</name>
  <url>http://maven.apache.org</url>
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <jackson.version>2.9.5</jackson.version>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>${jackson.version}</version>
    </dependency>
    <dependency>
      <!-- Note: core-annotations version x.y.0 is generally compatible with
         (identical to) version x.y.1, x.y.2, etc. -->
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-annotations</artifactId>
      <version>${jackson.version}</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
      <version>${jackson.version}</version>
    </dependency>
  </dependencies>
  <build>
    <plugins>
      <plugin>
        <!-- Build an executable JAR -->
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-jar-plugin</artifactId>
        <version>3.1.0</version>
        <configuration>
          <archive>
            <manifest>
              <addClasspath>true</addClasspath>
              <mainClass>alex.test.App</mainClass>
            </manifest>
          </archive>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

The program compiles fine when I type mvn clean package, and I can see the jar file created inside the target folder. But when I try to run that jar file by typing java -jar test-0.0.1-SNAPSHOT.jar from there, it complains that it can't find the dependencies. It gives me an error like this.

    Exception in thread "main" java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/ObjectMapper
        at alex.test.App.main(App.java:20)
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.databind.ObjectMapper
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:582)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:190)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:499)
        ... 1 more

So, my question is, what changes I need to make, to make sure all dependencies end up inside the target folder, and I don't get this error anymore.

have you checked the size of the jar that you are trying to run? it must be in some KB's it means that your dependencies have not been downloaded. And to download and have clean compilation , run either of the two "mvn clean install or mvn clean install -DskipTests" is what i would prefer — Shubham, Sep 26 '18 at 15:47
the reason you are getting Exception in thread "main" java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/ObjectMapper is because it is looking for this class in the package that you have mentioned and is not available as a dependency — Shubham, Sep 26 '18 at 15:49
Take a look at this: https://stackoverflow.com/questions/574594/how-can-i-create-an-executable-jar-with-dependencies-using-maven — Nima Ajdari, Sep 26 '18 at 15:51

score 2 · Answer 1 · answered Sep 26 '18 at 15:57

<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>sample</groupId>
<artifactId>com.sample.project</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>com.sample.project</name>
<url>http://maven.apache.org</url>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>3.8.1</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.9.7</version>
    </dependency>

    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-annotations</artifactId>
        <version>2.9.7</version>
    </dependency>

    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.9.7</version>
    </dependency>
</dependencies>
<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>
            <version>3.1.0</version>
            <configuration>
                <archive>
                    <manifest>
                        <addClasspath>true</addClasspath>
                        <mainClass>alex.test.App</mainClass>
                    </manifest>
                </archive>
            </configuration>
        </plugin>
    </plugins>
</build>

try this as an answer change the group id it will work , the problem with your pom is you are not specifying the version of the jars that you are building simply you can change ${jackson.version} to any version that you require and your existing pom will work

score 1 · Accepted Answer · answered Sep 26 '18 at 15:43

Try to add this to your pom.xml:

<project>
...
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>3.0.0</version>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass>com.yourpackage.MainClass</mainClass>
                            <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
                            <addDefaultSpecificationEntries>true</addDefaultSpecificationEntries>
                        </manifest>
                    </archive>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                </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>
</project>

It will generate a runnable jar file inside your target with all dependencies included. Be sure to set the path to your main class.

I just realized I took this code a long time ago from https://stackoverflow.com/questions/574594/how-can-i-create-an-executable-jar-with-dependencies-using-maven. So I should leave these credits here. — saucecode, Sep 26 '18 at 15:54
I guess this produces a Fat jar, where the jar contains all the dependent libraries. — AlexScalar, Sep 26 '18 at 16:03
@AlexScalar It does. This solution is meant for standalone runnable jars. — saucecode, Sep 26 '18 at 16:09

score 0 · Answer 3 · answered Sep 26 '18 at 17:13

Try Maven shade plugin

<?xml version="1.0"?>
<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>alex</groupId>
  <artifactId>test</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>
  <name>test</name>
  <url>http://maven.apache.org</url>
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <jackson.version>2.9.5</jackson.version>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>${jackson.version}</version>
    </dependency>
    <dependency>
      <!-- Note: core-annotations version x.y.0 is generally compatible with
         (identical to) version x.y.1, x.y.2, etc. -->
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-annotations</artifactId>
      <version>${jackson.version}</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
      <version>${jackson.version}</version>
    </dependency>
  </dependencies>
  <build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-shade-plugin</artifactId>
            <version>3.1.1</version>
            <executions>
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>shade</goal>
                    </goals>
                    <configuration>
                        <transformers>
                            <transformer
                                    implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                <mainClass><!-- Path to main class --></mainClass>
                            </transformer>
                        </transformers>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
  </build>
 </project>

This plugin will be helpful in resolving the clashes in class names with same name in multiple dependencies.

How to tell Maven project to include dependencies in the target folder?

3 Answers3