Spark: java.lang.NoClassDefFoundError: spark/Request

[anxiaoyi]

Java Class:

import static spark.Spark.*;

public class HelloWorld {
    public static void main(String[] args) {
        get("/hello", (req, res) -> "Hello World");
    }
}

pom.xml:

<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.zk.HelloSpark</groupId>
  <artifactId>HelloSpark</artifactId>
  <version>1.0</version>

  <properties>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

  <dependencies>

    <dependency>
      <groupId>com.sparkjava</groupId>
      <artifactId>spark-core</artifactId>
      <version>2.5.4</version>
    </dependency>

    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-simple</artifactId>
      <version>1.7.21</version>
    </dependency>

  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>2.3.2</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>single</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <descriptorRefs>
            <!-- This tells Maven to include all dependencies -->
            <descriptorRef>jar-with-dependencies</descriptorRef>
          </descriptorRefs>
          <archive>
            <manifest>
              <mainClass>HelloWorld</mainClass>
            </manifest>
          </archive>
        </configuration>
      </plugin>
    </plugins>
  </build>

</project>

After I execute the command mvn package, and the command java -cp target/HelloSpark-1.0.jar HelloWorld, But I get the following exception:

Exception in thread "main" java.lang.BootstrapMethodError: java.lang.NoClassDefFoundError: spark/Request
    at HelloWorld.main(HelloWorld.java:5)
Caused by: java.lang.NoClassDefFoundError: spark/Request
    ... 1 more
Caused by: java.lang.ClassNotFoundException: spark.Request
    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

What should I do to fix this problem ?

[DOFandersolsen]

This is because you are not including the spark library inside your .jar and Java doesn't know where else to search.

I have solved it using the maven-shaded-plugin, which embeds every dependency inside your jar.
http://www.mkyong.com/maven/create-a-fat-jar-file-maven-shade-plugin/

<build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.6.0</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
            <!-- Maven Shade Plugin -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.4.3</version>
                <configuration>
                    <filters>
                        <filter>
                            <artifact>*:*</artifact>
                            <excludes>
                                <exclude>META-INF/*.SF</exclude>
                                <exclude>META-INF/*.DSA</exclude>
                                <exclude>META-INF/*.RSA</exclude>
                            </excludes>
                        </filter>
                    </filters>
                    <!-- Additional configuration. -->
                </configuration>
                <executions>
                    <!-- Run shade goal on package phase -->
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <transformers>
                                <!-- add Main-Class to manifest file -->
                                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                    <mainClass>HelloWorld</mainClass>
                                </transformer>
                            </transformers>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
</build>

Hope this helps!

Also, your maven-compiler-plugin is way behind, if you are running Maven 3.3.9, the newest version would be 3.6.0

[jakaarl]

Building a JAR with dependencies using assembly plugin should work just as well. Of course should check the contents of the JAR to see that it's as expected.

[jakaarl]

@anxiaoyi you're using the wrong JAR (yes, should've spotted it the first time around). The correct JAR in this case would be called HelloSpark-1.0-jar-with-dependencies.jar.

Please confirm that it works and close the issue if so.