How To Install OpenCV 3.3+ with Java on Mac

I spent a couple hours trying to resolve an UnsatisfiedLinkError with OpenCV and Java on Mac, I found the solution.

If you installed OpenCV on Mac via brew, such as by using

brew install opencv

Then you may be getting an error when trying to use System.loadLibrary(Core.NATIVE_LIBRARY_NAME) that says something like:

UnsatisfiedLinkError: no opencv_java331 in java.library.path

The solution to this is to reinstall OpenCV with the proper Java libs. Try the following steps:

brew install ant
brew edit opencv
# change -DBUILD_opencv_java=OFF to ON
brew uninstall opencv # if you installed opencv before
brew install --build-from-source opencv # Note: this may take a long time

You may also need to point your IDE to the Java lib location by using a JVM arg such as:

-Djava.library.path=/usr/local/Cellar/opencv3/XXX/share/OpenCV/java

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