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running java class issue [closed]

asked 2016-11-09 17:14:07 -0500

aliyesami gravatar image

updated 2016-11-09 22:41:26 -0500

I am following the popular DetectFaceDemo tutorial but I cant seem to run the packaged jar . DetectFaceDemo

I have placed the following files in their respect directories as shown below :

[root@hadoop1 java]# pwd
[root@hadoop1 java]#
[root@hadoop1 java]# ls
build.sbt  lib  project  target
[root@hadoop1 java]#
[root@hadoop1 java]# ls  lib  opencv-249.jar
[root@hadoop1 java]#
[root@hadoop1 java]# cd ..
[root@hadoop1 main]# pwd
[root@hadoop1 main]# ls
java  origscala  resources
[root@hadoop1 main]# ls resources
AverageMaleFace.jpg  img1.png  img2.png  lbpcascade_frontalface.xml  lena.png
[root@hadoop1 main]#

I am getting error when I run the jar , I have a feeling the code is not picking up the image and the xml file from the src/main/resources folder ? I have though provided the absolute path to the resource folder.

[root@hadoop1 java]# sbt run
[info] Set current project to DetectFaceDemo (in build file:/root/openCV/opencv/samples/java/sbt/src/main/java/)
[info] Running HelloOpenCV
[info] Hello, OpenCV
[info] Running DetectFaceDemo
[error] Exception in thread "main" java.lang.NullPointerException
[error]         at
[error]         at HelloOpenCV.main(
java.lang.RuntimeException: Nonzero exit code returned from runner: 1
        at scala.sys.package$.error(package.scala:27)
[trace] Stack trace suppressed: run last compile:run for the full output.
[error] (compile:run) Nonzero exit code returned from runner: 1
[error] Total time: 1 s, completed Nov 9, 2016 11:20:34 PM

the source code is below:

[root@hadoop1 java]# more
import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.MatOfRect;
import org.opencv.core.Point;
import org.opencv.core.Rect;
import org.opencv.core.Scalar;
import org.opencv.highgui.Highgui;
import org.opencv.objdetect.CascadeClassifier;

// Detects faces in an image, draws boxes around them, and writes the results
// to "faceDetection.png".
class DetectFaceDemo {
  public void run() {
    System.out.println("\nRunning DetectFaceDemo");

    // Create a face detector from the cascade file in the resources
    // directory.
    CascadeClassifier faceDetector = new CascadeClassifier(getClass().getResource("/root/openCV/opencv/samples/java/sbt/src/main/resources/lbpcascade_frontalface.xml").getPath());
    Mat image = Highgui.imread(getClass().getResource("/root/openCV/opencv/samples/java/sbt/src/main/resources/lena.png").getPath());

    // Detect faces in the image.
    // MatOfRect is a special container class for Rect.
    MatOfRect faceDetections = new MatOfRect();
    faceDetector.detectMultiScale(image, faceDetections);

    System.out.println(String.format("Detected %s faces", faceDetections.toArray().length));

    // Draw a bounding box around each face.
    for (Rect rect : faceDetections.toArray()) {
        Core.rectangle(image, new Point(rect.x, rect.y), new Point(rect.x + rect.width, rect.y + rect.height), new Scalar(0, 255
, 0));

    // Save the visualized detection.
    String filename = "faceDetection.png";
    System.out.println(String.format("Writing %s", filename));
    Highgui.imwrite(filename, image);

public class HelloOpenCV {
  public static void main(String[] args) {
    System.out.println("Hello, OpenCV");

    // Load the native library.
    System.loadLibrary(Core ...
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Closed for the following reason the question is answered, right answer was accepted by aliyesami
close date 2016-11-19 19:03:45.265894


found the solution online : put the following in the code to finD the classpath and copy the "xml" and "png" files to this location .


aliyesami gravatar imagealiyesami ( 2016-11-10 00:23:00 -0500 )edit

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answered 2016-11-12 01:02:12 -0500

aliyesami gravatar image

found the solution online : put the following in the code to finD the classpath and copy the "xml" and "png" files to this location .


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Asked: 2016-11-09 17:14:07 -0500

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Last updated: Nov 12 '16