I am trying to learn JavaFX with the library OpenCV for my degree. I want to make a program that detects people. We can name it people counter. I saw some videos already and I want to do that too.
The problem is that I have to start to learn JavaFX and the library OpenCV. So I started to create a simple project that starts / pause the webcam and take a snapshot. I saw someone on youtube doing this and I started to recreate it.
The problem is that I have this error:
Exception in Application start method
java.lang.reflect.InvocationTargetException
My code is:
Main
package application;
import javafx.application.Application;
import javafx.stage.Stage;
import javafx.stage.WindowEvent;
import javafx.scene.Scene;
import javafx.scene.layout.BorderPane;
import javafx.fxml.FXMLLoader;
public class Main extends Application {
@Override
public void start(Stage primaryStage) {
try {
BorderPane root = (BorderPane) FXMLLoader.load(getClass().getResource("Camera.fxml"));
Scene scene = new Scene(root, 400, 400);
scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
primaryStage.setScene(scene);
primaryStage.show();
} catch(Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
launch(args);
}
}
CameraController
package application;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import javax.imageio.ImageIO;
import javafx.embed.swing.SwingFXUtils;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.image.ImageView;
import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.MatOfByte;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.videoio.VideoCapture;
public class CameraController {
// definitions
@FXML
private Button btn_start, btn_pause, btn_snapshot;
@FXML
private ImageView imgView;
private DaemonThread myThread = null;
int count = 0;
VideoCapture webSource = null;
Mat frame = new Mat();
MatOfByte mem = new MatOfByte(); /// start button
@FXML
protected void startClick(ActionEvent event) {
webSource =new VideoCapture(0);
myThread = new DaemonThread();
Thread t = new Thread(myThread);
t.setDaemon(true);
myThread.runnable = true;
t.start();
btn_start.setDisable(true);
btn_pause.setDisable(false); // stop button
}
@FXML
protected void pauseClick(ActionEvent event) {}
@FXML
protected void snapshotClick(ActionEvent event) {}
class DaemonThread implements Runnable {
protected volatile boolean runnable = false;
@Override
public void run() {
synchronized (this) {
while (runnable) {
if (webSource.grab()) {
try {
webSource.retrieve(frame);
Imgcodecs.imencode(".bmp", frame, mem);
Image im = ImageIO.read(new ByteArrayInputStream(mem.toArray()));
BufferedImage buff = (BufferedImage) im;
imgView.setImage(SwingFXUtils.toFXImage(buff, null));
if (!runnable) {
System.out.println("Going to wait()");
this.wait();
}
} catch (Exception ex) {
System.out.println("Error");
}
}
}
}
}
}
/////////////////////////////////////////////////////////
}
}
The problem is on this line:
BorderPane root = (BorderPane) FXMLLoader.load(getClass().getResource("Camera.fxml"));
Scene scene = new Scene(root,400,400);
Full console error:
Exception in Application start method
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at sun.launcher.LauncherHelper$FXHelper.main(Unknown Source)
Caused by: java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$155(LauncherImpl.java:182)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.UnsatisfiedLinkError: org.opencv.core.Mat.n_Mat()J
at org.opencv.core.Mat.n_Mat(Native Method)
at org.opencv.core.Mat.<init>(Mat.java:24)
at application.CameraController.<init>(CameraController.java:34)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at sun.reflect.misc.ReflectUtil.newInstance(Unknown Source)
at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:927)
at javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:971)
at javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:220)
at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:744)
at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2707)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3214)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
at application.Main.start(Main.java:15)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
... 1 more
Exception running application application.Main
Thank you in advance!
I fixed the problem by just adding System.loadLibrary(Core.NATIVE_LIBRARY_NAME):
public static void main(String[] args) {
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
launch(args);
}