Cannot invoke "org.oscim.backend.CanvasAdapter.newCanvasImpl()" because "org.oscim.backend.CanvasAdapter.g" is null

[codewriter3000]

I'm getting this error when debugging:

Exception in thread "main" java.lang.NullPointerException: Cannot invoke "org.oscim.backend.CanvasAdapter.newCanvasImpl()" because "org.oscim.backend.CanvasAdapter.g" is null
	at org.oscim.backend.CanvasAdapter.newCanvas(CanvasAdapter.java:87)
	at UserInterface.showUI(UserInterface.java:17)
	at UserInterface.<init>(UserInterface.java:11)
	at UserInterface.main(UserInterface.java:25)

Here is my maven:

<?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>Magellan</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>15</maven.compiler.source>
        <maven.compiler.target>15</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.mapsforge</groupId>
            <artifactId>vtm-desktop</artifactId>
            <version>0.16.0</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.5</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.5</version>
        </dependency>
    </dependencies>

</project>

And this is my code:

import org.oscim.awt.AwtGraphics;
import org.oscim.backend.canvas.Canvas;

import javax.swing.*;
import java.awt.*;


public class UserInterface {


    public UserInterface(){ showUI(); }

    private void showUI(){
        JFrame jFrame = new JFrame();
        jFrame.setSize(500, 500);

        Canvas canvas = AwtGraphics.newCanvas();
        Container container = jFrame.getContentPane();
        container.setLayout(new BorderLayout());
        container.add((Component) canvas);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    }

    public static void main(String[] args){ new UserInterface(); }
}

[devemux86]

See the vtm-playground examples for how to initialize and use VTM on desktop.

[codewriter3000]

I copied and pasted the MapzenTest class from the source code into my program. I believe that the playground is outdated. I had to use vtm-desktop 0.11.1 since it's the latest version with the GdxMapApp class.

Something else that I tried doing was to clone the vtm-playground into a new project, but I would get this error when I would download the dependencies:

A problem occurred configuring project ':vtm-web-app'.
> Could not create task ':vtm-android:generateLintModuleInfo'.
   > Failed to install the following Android SDK packages as some licences have not been accepted.
        patcher;v4 SDK Patch Applier v4
        platforms;android-30 Android SDK Platform 30
        build-tools;30.0.3 Android SDK Build-Tools 30.0.3
        emulator Android Emulator
        tools Android SDK Tools
     To build this project, accept the SDK license agreements and install the missing components using the Android Studio SDK Manager.
     Alternatively, to transfer the license agreements from one workstation to another, see http://d.android.com/r/studio-ui/export-licenses.html

[devemux86]

Cloning the repository, opening with IDEA and running an example like MapilionMvtTest, everything works fine.

You probably need to debug your IDE and working environment.

See the integration guide for to integrate the library in your project.