问题
I'm working on an Android project which uses NDK, in which I have used opencv for some capture and image effects stuff. Here's how my Android.mk look like:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
include path/to/OpenCV.mk
LOCAL_MODULE := Scanner
LOCAL_SRC_FILES := scan.cpp
LOCAL_LDLIBS += -lz -lm -llog -landroid -ldl -lstdc++
LOCAL_LDFLAGS += -ljnigraphics -fexceptions -std=c++11 -L$(LOCAL_PATH)/sdk/native/jni/libs/armeabi-v7a -L$(LOCAL_PATH)/sdk/native/jni/3rdparty/libs/armeabi-v7a -I$(LOCAL_PATH)/sdk/native/jni/include -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/core -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/calib3d -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/contrib -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/features2d -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/flann -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/highgui -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/imgproc -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/legacy -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/ml -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/objdetect -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/ocl -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/photo -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/stitching -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/superres -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/ts -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/video -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2/videostab -I$(LOCAL_PATH)/sdk/native/jni/include/opencv2
LOCAL_STATIC_LIBRARIES := opencv_shape opencv_stitching opencv_objdetect opencv_superres opencv_videostab opencv_calib3d opencv_features2d opencv_highgui opencv_videoio opencv_imgcodecs opencv_video opencv_photo opencv_ml opencv_flann opencv_imgproc opencv_core opencv_ts IlmImf libjasper libjpeg libpng libtiff libwebp tbb
include $(BUILD_SHARED_LIBRARY)
Though I'm linking all opencv libraries and specifying the correct path(verified it by chaning paths) I'm getting the following linker error:
../sdk/native/jni/include/opencv2/core/mat.hpp:335: error: undefined reference to 'cv::_OutputArray::_OutputArray(cv::Mat&)'
jni/scan.cpp:33: error: undefined reference to 'cv::_InputArray::_InputArray(cv::Mat const&)'
jni/scan.cpp:33: error: undefined reference to 'cv::_OutputArray::_OutputArray(cv::Mat&)'
jni/scan.cpp:65: error: undefined reference to 'cv::_InputArray::_InputArray(cv::Mat const&)'
jni/scan.cpp:65: error: undefined reference to 'cv::_InputArray::_InputArray(cv::Mat const&)'
jni/scan.cpp:72: error: undefined reference to 'cv::_InputArray::_InputArray(cv::Mat const&)'
jni/scan.cpp:48: error: undefined reference to 'cv::_OutputArray::_OutputArray(cv::Mat&)'
jni/scan.cpp:51: error: undefined reference to 'cv::_OutputArray::_OutputArray(cv::Mat&)'
jni/scan.cpp:58: error: undefined reference to 'cv::findContours(cv::_OutputArray const&, cv::_OutputArray const&, int, int, cv::Point_<int>)'
..sdk/native/jni/include/opencv2/core/mat.hpp:276: error: undefined reference to 'vtable for cv::_OutputArray'
..Android/sdk/ndk-bundle/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: the vtable symbol may be undefined because the class is missing its key function
..sdk/native/jni/include/opencv2/core/mat.hpp:276: error: undefined reference to 'vtable for cv::_OutputArray'
..Android/sdk/ndk-bundle/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: the vtable symbol may be undefined because the class is missing its key function
jni/scan.cpp:162: error: undefined reference to 'cv::findContours(cv::_OutputArray const&, cv::_OutputArray const&, int, int, cv::Point_<int>)'
..sdk/native/jni/include/opencv2/core/mat.hpp:276: error: undefined reference to 'vtable for cv::_OutputArray'
/Users/mtsindia/Library/Android/sdk/ndk-bundle/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: the vtable symbol may be undefined because the class is missing its key function
..sdk/native/jni/include/opencv2/core/mat.hpp:276: error: undefined reference to 'vtable for cv::_OutputArray'
..Android/sdk/ndk-bundle/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: the vtable symbol may be undefined because the class is missing its key function
jni/scan.cpp:261: error: undefined reference to 'vtable for cv::_InputArray'
..Android/sdk/ndk-bundle/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: the vtable symbol may be undefined because the class is missing its key function
jni/scan.cpp:296: error: undefined reference to 'cv::Exception::Exception(int, std::string const&, std::string const&, std::string const&, int)'
jni/scan.cpp:297: error: undefined reference to 'cv::Exception::Exception(int, std::string const&, std::string const&, std::string const&, int)'
jni/scan.cpp:298: error: undefined reference to 'cv::Exception::Exception(int, std::string const&, std::string const&, std::string const&, int)'
jni/scan.cpp:299: error: undefined reference to 'cv::Exception::Exception(int, std::string const&, std::string const&, std::string const&, int)'
This is the link where I downloaded the scanner app demo and made modifications in scan.cpp file and trying to rebuild the library.
I have created ndk-build as an external tool in Android studio, verified the ndk path too. What am I missing here? Any help would be appreciated.
回答1:
Fixed it. I dont know the exact reason how it get fixed. I reverted all the changes I've made in Android.mk , Application.mk and OpenCV.mk, Now my Adnroid.mk looks like this:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
OPENCV_INSTALL_MODULES:=on
include $(LOCAL_PATH)/sdk/native/jni/OpenCV.mk
LOCAL_MODULE := Scanner
LOCAL_SRC_FILES := scan.cpp
LOCAL_LDLIBS += -lm -llog -landroid
LOCAL_LDFLAGS += -ljnigraphics
include $(BUILD_SHARED_LIBRARY)
And Application.mk:
APP_STL := stlport_static
APP_CPPFLAGS := -frtti -fexceptions
APP_ABI := all
APP_PLATFORM := android-14
And here's how my OpenCV.mk looks like:
https://pastebin.com/zuqM6tbu
I guess I have missed specyfying the correct path or my library files(.so and .a) might be of different versions than the header files included. If anyone got other ideas, please post a comment.
来源：https://stackoverflow.com/questions/47903357/android-studio-ndk-linker-error-undefined-reference-to-cv-outputarray-outpu