void* SDL_AndroidGetActivity(void)

// Calls the void MyActivity.showHome() method of the Java instance of the activity.
void showHome(void)
{
    // retrieve the JNI environment.
    JNIEnv* env = (JNIEnv*)SDL_AndroidGetJNIEnv();

    // retrieve the Java instance of the SDLActivity
    jobject activity = (jobject)SDL_AndroidGetActivity();

    // find the Java class of the activity. It should be SDLActivity or a subclass of it.
    jclass clazz( env->GetObjectClass(activity) );

    // find the identifier of the method to call
    jmethodID method_id = env->GetMethodID( clazz, "showHome", "()V" );

    // effectively call the Java method
    env->CallVoidMethod( activity, method_id );
    
    // clean up the local references.
    env->DeleteLocalRef(activity);
}