java.lang.UnsatisfiedLinkError: org.opencv.core.Core

Question

I'm trying for too long to setup a Java env with OpenCV, I was able to do it for Android but not for a simple Java project.

I have vscode with all the extensions, and set up a project with the jar in the .classpath

And I get:

java.lang.UnsatisfiedLinkError: org.opencv.core.Core

I understand that the problem is that the actual OpenCV-420.dll is not set up, but I cannot find any documentation on how to set it up in vscode.

I tried in Ecplise ( https://opencv-java-tutorials.readthedocs.io/en/latest/01-installing-opencv-for-java.html ), but I get the same error

Answer 1

This works for me:

package app;

import java.lang.reflect.Field;

import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;

// import org.opencv.core.Core;
public class App {
    public static void main(String[] args) {
        try {
            App.loadOpenCV_Lib();
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
        Mat mat = Mat.eye(3, 3, CvType.CV_8UC1);
        System.out.println("mat = " + mat.dump());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void loadOpenCV_Lib() throws Exception {
        // get the model
        String model = System.getProperty("sun.arch.data.model");
        // the path the .dll lib location
        String libraryPath = "D:/opencv/build/java/x86/";
        // check for if system is 64 or 32
        if(model.equals("64")) {
            libraryPath = "D:/opencv/build/java/x64/";
        }
        // set the path
        System.setProperty("java.library.path", libraryPath);
        Field sysPath = ClassLoader.class.getDeclaredField("sys_paths");
        sysPath.setAccessible(true);
        sysPath.set(null, null);
        // load the lib
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
    }
}

explain: the loadOpenCV_Lib will import the package on the fly with reflect