CODEWITHSUNDEEP
javaopencvterminal
Felix Eder
Felix Eder

Reputation: 325

JNI error has occurred when running java with OpenCV from terminal

I'm trying to compile a java-program written with OpenCV 3.2.0 from the terminal. It was originally written in Eclipse with OpenCV as a user library. I compile it with this command:

javac -cp /opencv-3.2.0-java/build/bin/ *.java

It works with no error, the -cp command shows the path to the OpenCV jar. I then try to run everything with this command:

java -Djava.library.path="/opencv-3.2.0-java/build/lib" -cp jar/opencv-320.jar -classpath . Main

It gives me this error:

Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.NoClassDefFoundError: org/opencv/core/Mat
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
    at java.lang.Class.privateGetMethodRecursive(Class.java:3048)
    at java.lang.Class.getMethod0(Class.java:3018)
    at java.lang.Class.getMethod(Class.java:1784)
    at sun.launcher.LauncherHelper.validateMainClass(LauncherHelper.java:544)
    at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:526)
Caused by: java.lang.ClassNotFoundException: org.opencv.core.Mat
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

I searched for solutions to this problem and came to the conclusion that it had something to do with native libraries. I use the -Djava parameter to link to the path of the library files from OpenCV, but it still doesn't work somehow. How do I fix this?

EDIT:

All the .java files are on a folder on the desktop. This is were the Main file is included. For example:

home/pi/Desktop/MultiSensor_v2.0_Java/Main.java

The path to the OpenCV jar:

/home/pi/Desktop/MultiSensor_v2.0_Java/opencv-3.2.0-java/build/bin/opencv-320.jar

The path to OpenCV native libraries:

/home/pi/Desktop/MultiSensor_v2.0_Java/opencv-3.2.0-java/build/lib

Upvotes: 0

Views: 955

Answers (1)

Jorn Vernee
Jorn Vernee

Reputation: 33895

-cp is short for -classpath. So I suspect that when you use both, the second one overwrites the first.

You can have multiple entries on the class path separated by : as stated in the documentation: Setting the class path. (actually, it looks like that is a typo in the doc, and it should be ; as a separator. You could try both)

If you execute your command from the directory home/pi/Desktop/MultiSensor_v2.0_Java/ that would make:

java -Djava.library.path="opencv-3.2.0-java/build/lib" -cp .:opencv-3.2.0-java/build/bin/opencv-320.jarr Main

Upvotes: 1

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