java cannot run processing, quits with the following error: Error: Could not find or load main class

ayatana

Here is my MWE:

import java.lang.*;
import processing.core.PApplet;

public class test extends PApplet{

    public static void main(String[]args){
        PApplet.main("test");
    }

    public void settings(){
        size(500, 500, P2D);
    }

    public void setup(){
        background(255);
    }

    public void draw(){
        ellipse(mouseX, mouseY, 50, 50);
    }
}

I compile it with,

javac -classpath processing-3.3.7/core/library/core.jar test.java

It compiles without any warnings, or erros. But when I try to run it,

java test

I get the error,

Error: Could not find or load main class

What to do? I also tried adding class path when running, but it didn't help.

kfrajer

If you create a simple sketch in the PDE and then export it from there, you will see that you need other jar files. This is important specially when you are working with the P2D renderer.

---

Have you tried using processing-java to create your executable?

---

Before running the command, we need to implement the following changes:

• Class names start with upper case as in Test and not test.
• As a mention above, OpenGL requires extra libs. For the time being, drop the P2D parameter in your size(). After all, this is just a demo to show how to run it using javac.

• Your main should look like this (From HappyCoding @KevinWorkman):

  public static void main(String[]args){
      String[] processingArgs = {"Test"};
      Test mySketch = new Test();
      PApplet.runSketch(processingArgs, mySketch);
  }
  

Now you execute:

javac -cp ".;C:\Users\C\Downloads\downloaded_installers\P3\current\processing\core\library\core.jar" Test.java

java -cp ".;C:\Users\C\Downloads\downloaded_installers\P3\current\processing\core\library\core.jar" Test

Note that if you execute javac -help you will see some other convenient arguments Notice in Windows you use ; while in Linux you would use :

This should get you started.

Kf

---

Relevant posts:

http://happycoding.io/tutorials/java/processing-in-java
https://github.com/processing/processing/wiki/Command-Line
https://forum.processing.org/two/discussion/7375/how-to-compile-a-sketch-to-java
https://forum.processing.org/two/discussion/23924/handling-command-line-arguments-in-a-sketch
https://www.programcreek.com/2014/01/compile-and-run-java-in-command-line-with-external-jars/

https://rishisoftwareblog.wordpress.com/2013/02/12/compiling-and-executing-a-processing-sketch-as-a-java-class/

https://forum.processing.org/two/discussion/21204/using-launch4j-jarmatey-with-processing
http://launch4j.sourceforge.net/
https://github.com/processing/processing/tree/master/java/application/launch4j

ayatana

adding .: to the beginning of the classpath helped. Nothing else need to be changed. Thanks.