make: *** No rule to make target `jni/NDKDemo2.cpp', needed by `.../objs/NDKDemo/NDKDemo2.o'. stop

make: *** No rule to make target `jni/NDKDemo2.cpp', needed by 

`obj/local/arm64-v8a/objs/NDKDemo/NDKDemo2.o'.  Stop.

错误原因：Android.mk的变量LOCAL_SRC_FILES := NDKDemo2.cpp

                找不到jni目录下的NDKDemo2.cpp文件；

解决方案：重新设置LOCAL_SRC_FILES 对应的*.cpp文件；

例如：

把

LOCAL_SRC_FILES := NDKDemo2.cpp

修改为：

LOCAL_SRC_FILES := NDKDemo.cpp