Processing 4 error: WARNING: Illegal reflective access by gab.opencv.OpenCV

Question

I'm trying to use OpenCV with Processing 4 on a MAC with Catalina. However, I am getting the following error:

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by gab.opencv.OpenCV (file:/Users/mmemmo/Documents/Processing/libraries/opencv_processing/library/opencv_processing.jar) to field java.lang.ClassLoader.sys_paths

when I run this code

import gab.opencv.*;
import processing.video.*;
import java.awt.*;

Capture video;
OpenCV opencv;

void setup() {
  size(640, 480);
  video = new Capture(this, 640/2, 480/2);
  opencv = new OpenCV(this, 640/2, 480/2);
  //CASCADE_EYE
  opencv.loadCascade(OpenCV.CASCADE_FRONTALFACE);  
 // opencv.loadCascade(OpenCV.CASCADE_EYE);  

  video.start();
}

void draw() {
  scale(2);
  opencv.loadImage(video);

  image(video, 0, 0 );

  noFill();
  stroke(0, 255, 0);
  strokeWeight(3);
  Rectangle[] faces = opencv.detect();
  println(faces.length);

  for (int i = 0; i < faces.length; i++) {
    println(faces[i].x + "," + faces[i].y);
    rect(faces[i].x, faces[i].y, faces[i].width, faces[i].height);
  }
  
  if(faces.length > 0 ){
    println("Hello Human");enter code here
  }
}

void captureEvent(Capture c) {
  c.read();
}

I know Processing has camera issues with Catalina. That doesn't seem to be the issue here. I was able to get the camera working just fine in other sketches.

I would appreciate any feedback. Thanks.

score 3 · Accepted Answer · answered Feb 20 '21 at 17:51

The module system introduced in Java 9 has more limitations in what modules can use of the functionality of other modules. See this question and answers for more information: what is an illegal reflective access

Is there a specific reason that you are using Processing 4? There are only alpha releases available at the moment, so I would use Processing 3 if possible. When I try to run your code in Processing 4, I get the same error as you. When I run your code in Processing 3.5.4 (on Ubuntu), it runs without any issues and facial recognition is working. I would recommend giving Processing 3 a try.

Thank you for your response. That was very helpful. I was using Processing 4 because there were reported issues with all previous versions of processing and MAC OS Catalina. However. this worked with 3.5.4!! As a note, I did have to run it through terminal to get the camera to work. Otherwise, MAC OS doesn't give you permission to access the camera. Thanks again. — Matthew Memmo, Feb 20 '21 at 18:04

Jaegon Lee · Answer 2 · 2021-07-23T16:53:06.637

I modified opencv-processing library and it works with processing 4. Not perfect, but it works anyway. https://github.com/jaegonlee/opencv-processing/releases

The original opencv-processing library set library path with this code. But it doesn't work with Java 11(Processing 4), and causes warnings.

public static void setLibraryPath(String path) throws Exception {
    System.setProperty("java.library.path", path);

    //set sys_paths to null so that java.library.path will be reevalueted next time it is needed
    final Field sysPathsField = ClassLoader.class.getDeclaredField("sys_paths");
    sysPathsField.setAccessible(true);
    sysPathsField.set(null, null);
}

I deleted it and the warnings are gone. The modified library works fine with Processing IDE, but exported application does not work on macOS.

Link only answers are considered very low quality because it does not directly answer the question and solve the problem. Links are usually used as a reference to the answer that is given — I_love_vegetables, Jul 23 '21 at 07:31

Processing 4 error: WARNING: Illegal reflective access by gab.opencv.OpenCV

2 Answers2