Loading a jar-file with maven-shade-plugin

Question

I developed an API and a plugin with the dependency of the API. So I am using classes of the API. The problem is, I have to put the two jar-files in different folders and I am getting a ClassNotFoundException while starting the plugin. I asked a friend how to fix this and he anserwed, I should use maven-shade-plugin. But I do not know how to use this for my problem. This is the pom.xml of the project:

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>de.iltisauge</groupId>
  <artifactId>API-Plugin-Test</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>pom</packaging>
  <modules>
    <module>Test-API</module>
    <module>Test-Plugin</module>
  </modules>          
</project>

This is the pom.xml of my plugin-module:

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>de.iltisauge</groupId>
    <artifactId>API-Plugin-Test</artifactId>
    <version>0.0.1-SNAPSHOT</version>
  </parent>
  <artifactId>Test-Plugin</artifactId>
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>3.2.2</version>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>shade</goal>
            </goals>
            <configuration>
              <createDependencyReducedPom>false</createDependencyReducedPom>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  <dependencies>
    <dependency>
      <groupId>org.spigotmc</groupId>
      <artifactId>spigot-api</artifactId>
      <version>1.8.8-R0.1-SNAPSHOT</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>de.iltisauge</groupId>
      <artifactId>Test-API</artifactId>
      <version>0.0.1-SNAPSHOT</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>
</project>

and this is the pom.xml of the api-module:

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>de.iltisauge</groupId>
    <artifactId>API-Plugin-Test</artifactId>
    <version>0.0.1-SNAPSHOT</version>
  </parent>
  <artifactId>Test-API</artifactId>
</project>

and this is the console output:

[17:01:24 ERROR]: Could not load 'plugins\Test-Plugin-0.0.1-SNAPSHOT-shaded.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.NoClassDefFoundError: de/iltisauge/test/api/IHuman
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:135) ~[spigot1.8.8.jar:git-Spigot-db6de12-18fbb24]
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:329) ~[spigot1.8.8.jar:git-Spigot-db6de12-18fbb24]
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:251) [spigot1.8.8.jar:git-Spigot-db6de12-18fbb24]
        at org.bukkit.craftbukkit.v1_8_R3.CraftServer.loadPlugins(CraftServer.java:292) [spigot1.8.8.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.DedicatedServer.init(DedicatedServer.java:198) [spigot1.8.8.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:525) [spigot1.8.8.jar:git-Spigot-db6de12-18fbb24]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_241]
Caused by: java.lang.NoClassDefFoundError: de/iltisauge/test/api/IHuman
        at java.lang.Class.forName0(Native Method) ~[?:1.8.0_241]
        at java.lang.Class.forName(Unknown Source) ~[?:1.8.0_241]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64) ~[spigot1.8.8.jar:git-Spigot-db6de12-18fbb24]
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131) ~[spigot1.8.8.jar:git-Spigot-db6de12-18fbb24]
        ... 6 more
Caused by: java.lang.ClassNotFoundException: de.iltisauge.test.api.IHuman
        at java.net.URLClassLoader.findClass(Unknown Source) ~[?:1.8.0_241]
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:101) ~[spigot1.8.8.jar:git-Spigot-db6de12-18fbb24]
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:86) ~[spigot1.8.8.jar:git-Spigot-db6de12-18fbb24]
        at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_241]
        at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_241]
        at java.lang.Class.forName0(Native Method) ~[?:1.8.0_241]
        at java.lang.Class.forName(Unknown Source) ~[?:1.8.0_241]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64) ~[spigot1.8.8.jar:git-Spigot-db6de12-18fbb24]
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131) ~[spigot1.8.8.jar:git-Spigot-db6de12-18fbb24]
        ... 6 more

Post the API and Plugin pom please. I use spigot and multi-module maven aggregation/inheritance so i'm fairly certain I can help. — Jason, Apr 14 '20 at 15:08
Does this answer your question? [How can I create an executable JAR with dependencies using Maven?](https://stackoverflow.com/questions/574594/how-can-i-create-an-executable-jar-with-dependencies-using-maven) — J Fabian Meier, Apr 14 '20 at 15:08

Jason · Accepted Answer · 2020-04-14T15:29:09.433

0

Have the child module depend on the api. It is worth noting that the api's dependencies should be of scope provided so that when you shade your api with your module the dependencies don't overlap (just found this out).

<dependencies>
    <dependency>
        <groupId>de.iltisauge</groupId>
        <artifactId>API-Plugin-Test</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </dependency>
</dependencies>

edited Apr 14 '20 at 15:29

answered Apr 14 '20 at 15:24

Jason

5,154
2
12
22

Thank you very much. This fixed my problem. – IltisAuge Apr 14 '20 at 15:43
No problem man, i'm really glad I could help! Best of luck creating plugins! I hope i see you around spigot! – Jason Apr 14 '20 at 15:51

Loading a jar-file with maven-shade-plugin

1 Answers1