Error: Could not find or load main class com.github.shia5347.terratoolbox.App

Question

The problem

When I try to run my jar executable by specifying the slick2d library as a classpath: java -jar TerraToolBox-1.0-SNAPSHOT.jar -classpath org.newdawn.slick ; it gives an error saying Error: Could not find or load main class com.github.shia5347.terratoolbox.App. I also tried a simple hello world printing program rather than the slick2d window program extending BasicGame and that worked instead.

I had also tried adding <addClasspath>true</addClasspath> to the maven-jar-plugin section but it still did not work.

Using jdeps

jdeps TerraToolBox-1.0-SNAPSHOT.jar

TerraToolBox-1.0-SNAPSHOT.jar -> not found
TerraToolBox-1.0-SNAPSHOT.jar -> /usr/lib/jvm/java-8-openjdk/jre/lib/rt.jar
   com.github.shia5347.terratoolbox (TerraToolBox-1.0-SNAPSHOT.jar)
      -> java.lang                                          
      -> java.util.logging                                  
      -> org.newdawn.slick                                  not found

main

package com.github.shia5347.terratoolbox;

import java.util.logging.Level;
import java.util.logging.Logger;
import org.newdawn.slick.AppGameContainer;
import org.newdawn.slick.BasicGame;
import org.newdawn.slick.GameContainer;
import org.newdawn.slick.Graphics;
import org.newdawn.slick.SlickException;

public class App extends BasicGame
{
    public App(String gamename)
    {
        super(gamename);
    }

    @Override
    public void init(GameContainer gc) throws SlickException {}

    @Override
    public void update(GameContainer gc, int i) throws SlickException {}

    @Override
    public void render(GameContainer gc, Graphics g) throws SlickException
    {
        g.drawString("Howdy!", 10, 10);
    }

    public static void main(String[] args)
    {
        try
        {
            AppGameContainer appgc;
            appgc = new AppGameContainer(new App("Simple Slick Game"));
            appgc.setDisplayMode(640, 480, false);
            appgc.start();
        }
        catch (SlickException ex)
        {
            Logger.getLogger(App.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

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.github.shia5347.terratoolbox</groupId>
  <artifactId>TerraToolBox</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>TerraToolBox</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
  </properties>

  <dependencies>


    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>

<dependency>
    <groupId>javax.jnlp</groupId>
    <artifactId>jnlp-api</artifactId>
    <version>7.0</version>
    <scope>system</scope>
    <systemPath>/home/shahroz/netx-0.5/netx.jar</systemPath>
</dependency>


  <!-- https://mvnrepository.com/artifact/org.slick2d/slick2d-core -->
<dependency>
    <groupId>org.slick2d</groupId>
    <artifactId>slick2d-core</artifactId>
    <version>1.0.2</version>
</dependency>

  </dependencies>

  <build>
    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
      <plugins>
        <!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>3.1.0</version>
        </plugin>
        <!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.8.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.22.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-jar-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.5.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.8.2</version>
        </plugin>
        <!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
        <plugin>
          <artifactId>maven-site-plugin</artifactId>
          <version>3.7.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-project-info-reports-plugin</artifactId>
          <version>3.0.0</version>
        </plugin>

      <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <configuration>
                    <archive>
                        <manifest>
              <addClasspath>true</addClasspath>
                            <mainClass>com.github.shia5347.terratoolbox.App</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>


      </plugins>
    </pluginManagement>
  </build>
</project>

Manfiest file after setting addClasspath to true in pom.xml

Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Built-By: shahroz
Class-Path: slick2d-core-1.0.2.jar lwjgl-2.9.3.jar lwjgl-platform-2.9.
 3-natives-windows.jar lwjgl-platform-2.9.3-natives-linux.jar lwjgl-pl
 atform-2.9.3-natives-osx.jar jinput-2.0.5.jar jutils-1.0.0.jar jinput
 -platform-2.0.5-natives-linux.jar jinput-platform-2.0.5-natives-windo
 ws.jar jinput-platform-2.0.5-natives-osx.jar jorbis-0.0.17.jar
Created-By: Apache Maven 3.6.3
Build-Jdk: 1.8.0_275
Main-Class: com.github.shia5347.terratoolbox.App

Answer 1

Ok I just decided to use libgdx instead. It worked with maven using the maven-assembly-plugin. I justed typed mvn clean compile assembly:single which would then use the assembly plugin. Here is the plugin for it:

<plugin>
  <artifactId>maven-assembly-plugin</artifactId>
  <configuration>
    <archive>
      <manifest>
      <addClasspath>true</addClasspath>
        <mainClass>com.github.shia5347.terratoolbox.App</mainClass>
      </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>

Answer 2

First, make sure your java environment is configured correctly.

I think it may because the package name is added to the code, and the package name is also generated in the compiled .class file, but the com.github.shia5347.terratoolbox cannot be found at run time.

Turn to the folder terratoolbox in Terminal, then run javac -d. .\App.java, there'll be a .class file generated.

Then still under the folder terratoolbox, run java com.github.shia5347.terratoolbox.App.

Try this and see if the question goes away.