Why is the class not found?

Question

Java

I'm making a discord bot using maven and jda. I imported the dependencies according to the instructions on the github and there are no errors.

But the classes imported from jda are not shown in the input hint, nevertheless they were found through import when entered manually.

Error when trying to run in console:

Error: Could not find or load main class study.DiscordBot
Caused by: java.lang.NoClassDefFoundError: net/dv8tion/jda/api/hooks/ListenerAdapter

DiscordBot.java

package study;

import net.dv8tion.jda.api.JDABuilder;
import net.dv8tion.jda.api.entities.Activity;
import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
import net.dv8tion.jda.api.hooks.ListenerAdapter;

import javax.security.auth.login.LoginException;

public class DiscordBot extends ListenerAdapter {
    public static void main(String[] args) throws LoginException {
        JDABuilder bot = JDABuilder.createDefault("token");
        bot.setActivity(Activity.playing("java"));
        bot.addEventListeners(new DiscordBot());
        bot.build();
    }
    @Override
    public void onMessageReceived(MessageReceivedEvent event) {
        System.out.println(event.getMessage().getContentDisplay());
    }
}

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>org.example</groupId>
    <artifactId>discord-application</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>16</maven.compiler.source>
        <maven.compiler.target>16</maven.compiler.target>
    </properties>

    <dependencies>
        <!-- https://mvnrepository.com/artifact/net.dv8tion/JDA -->
        <dependency>
            <groupId>net.dv8tion</groupId>
            <artifactId>JDA</artifactId>
            <version>5.0.0-alpha.9</version>
        </dependency>
    </dependencies>
</project>

Answer 1

After a few hours of searching, I figured it out myself. If anyone has the same trouble, I leave the solution. In the maven pom file, you need to add the build block, add the maven assembly plugin. The full text looks like this, you can compare with the same text above.
In the line study.DiscordBot, replace the content with the path to your main class. The current version of the plugin can be found here .

<?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>org.example</groupId>
    <artifactId>discord-application</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>16</maven.compiler.source>
        <maven.compiler.target>16</maven.compiler.target>
    </properties>

    <dependencies>
        <!-- https://mvnrepository.com/artifact/net.dv8tion/JDA -->
        <dependency>
            <groupId>net.dv8tion</groupId>
            <artifactId>JDA</artifactId>
            <version>5.0.0-alpha.9</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>3.3.0</version>
                <configuration>
                    <!-- get all project dependencies -->
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                    <!-- MainClass in mainfest make a executable jar -->
                    <archive>
                        <manifest>
                            <mainClass>study.DiscordBot</mainClass>
                        </manifest>
                    </archive>

                </configuration>
                <executions>
                    <execution>
                        <id>make-assembly</id>
                        <!-- bind to the packaging phase -->
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>