hookup the rest of the android code

android/app/src/main/cpp/CMakeLists.txt

@@ -19,6 +19,11 @@ add_library( # Sets the name of the library.
              # Provides a relative path to your source file(s).
              native-lib.cpp )
 
+add_library(lib_foo SHARED IMPORTED)
+set_property(TARGET lib_foo PROPERTY IMPORTED_NO_SONAME 1)
+set_target_properties(lib_foo PROPERTIES IMPORTED_LOCATION ${CMAKE_CURRENT_SOURCE_DIR}/../jniLibs/${CMAKE_ANDROID_ARCH_ABI}/libfoo.so)
+include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../jniLibs/${CMAKE_ANDROID_ARCH_ABI}/)
+
 # Searches for a specified prebuilt library and stores the path as a
 # variable. Because CMake includes system libraries in the search path by
 # default, you only need to specify the name of the public NDK library
@@ -39,6 +44,8 @@ find_library( # Sets the name of the path variable.
 target_link_libraries( # Specifies the target library.
                        native-lib
 
+                       lib_foo
+
                        # Links the target library to the log library
                        # included in the NDK.
                        ${log-lib} )

android/app/src/main/cpp/native-lib.cpp

@@ -1,9 +1,16 @@
 #include <jni.h>
 #include <string>
 
+#include "libfoo.h"
+
 extern "C" {
     jstring
     Java_com_rogchap_foobar_MainActivity_reverse(JNIEnv* env, jobject, jstring str) {
-        return str;
+        const char* cstr = env->GetStringUTFChars(str, 0);
+        char* cout = reverse(const_cast<char*>(cstr));
+        jstring out = env->NewStringUTF(cout);
+        env->ReleaseStringUTFChars(str, cstr);
+        free(cout);
+        return out;
     }
 }