Trying to install v4l4j in Linux Mint15

[londrioca]

I'm trying to install a webcam barcode scanner JlinBar which requires v4l4j, of which I know absolutely nothing. I've downloaded & extracted this but get error message when I run "ant all":

    {[exec] v4l4j_FrameGrabber.c:25:17: fatal error: jni.h: No such file or directory

     [exec] compilation terminated.

     [exec] make: *** [v4l4j_FrameGrabber.o] Error 1

     [exec] make: Leaving directory `/home/paul/Downloads/v4l4j-0.9.1/src'

BUILD FAILED

/home/paul/Downloads/v4l4j-0.9.1/build.xml:92: exec returned: 2}

When I run "locate jni.h" I get:

{/home/paul/Downloads/adt-bundle-linux-x86_64-20131030/sdk/docs/training/articles/perf-jni.html

/home/paul/Downloads/opencv-2.4.8/platforms/android/service/engine/jni/JNIWrapper/HardwareDetector_jni.h

/home/paul/Downloads/opencv-2.4.8/platforms/android/service/engine/jni/JNIWrapper/OpenCVEngine_jni.h

/home/paul/Downloads/opencv-2.4.8/samples/android/face-detection/jni/DetectionBasedTracker_jni.h

/usr/lib/jvm/java-6-openjdk-amd64/include/jni.h

/usr/lib/jvm/java-7-openjdk-amd64/include/jni.h}

Google has no end of suggestions, all of which seem to assume more knowledge on the reader's part than is actually the case, I only half understand them. I'd appreciate it if someone could simply (operative word!) explain what's required.