opencv - Android - access native functions in a pre-compiled library -

i'd use native opencv function getthreshval_otsu_8u in android application. i've noticed external opencv java wrapper functions call functions defined native, don't have same names actual native functions. example:

java function:

double threshold(mat src, mat dst, double thresh, double maxval, int type) 

java "native" function:

private static native double threshold_0(long src_nativeobj, long dst_nativeobj, double thresh, double maxval, int type) 

c++ function:

double cv::threshold( inputarray _src, outputarray _dst, double thresh, double maxval, int type ) 

how can make similar native java function call getthreshval_otsu_8u? there way avoid rebuilding opencv libraries , "tunnel" existing .lib files?

if not case, first need set android project in order use java native interface (this link might help).

once set up, principle quite easy:

• you need create java native prototype in java code (e.g. public native void yourfunction();)
• the corresponding function must defined in c/c++ file (e.g. jniexport void jnicall java_your_package_javaclassname_yourfunction(jnienv * env, jobject obj);)
• you should able include opencv library in c/c++ code (e.g. #include <opencv2/core/core.hpp>)

the method want use (i.e. getthreshval_0tsu_8u) takes mat& parameter , returns double, means need adapt jni code correspondingly.