Calling getUnicodeChar method from C++ in Android

Question

I need unicode value of the key I pressed on Android's soft keyboard on C++ code but it looks like NativeActivity does not expose the 'getUnicodeChar' method. So I tried to call it with JNI but GetMethodID for that function returns '0'. This is my first time with the JNI so I might be doing something very wrong. I guess I have to give my 'AInputEvent' to Java somehow but I'm not sure how. This is the code I wrote:

JavaVM* java_vm = and_app->activity->vm; JNIEnv* jni_env = and_app->activity->env; JavaVMAttachArgs attach_args; attach_args.version = JNI_VERSION_1_6; attach_args.name = "NativeThread"; attach_args.group = NULL; jint result = java_vm->AttachCurrentThread(&jni_env, &attach_args); if(result == JNI_ERR) { return 0; } jclass class_key_event = jni_env->FindClass("android.view.KeyEvent"); jmethodID method_get_unicode_char = jni_env->GetMethodID(class_key_event, "getUnicodeChar", "()I"); int return_key = jni_env->CallIntMethod(class_key_event, method_get_unicode_char); java_vm->DetachCurrentThread(); return return_key;

Just FYI - this solution seems much better: stackoverflow.com/a/21130443/2926815 — Charles Lohr
– Charles Lohr, Commented Oct 1, 2019 at 23:44

mbrenon · Accepted Answer · 2013-07-29 14:50:09Z

The syntax for FindClass is quite special, and it requires what the JNI documentation calls a "a fully-qualified class name", which means a package name with the dots replaced by slashes.

In your case, using:

jclass class_key_event = jni_env->FindClass("android/view/KeyEvent");

should make your code work, or at least push it in the right direction!

Based on this, I can get the class_key_event, however, I can't seem to actually convert the AInputEvent in into a jobject sufficient for calling the IntMethod. ``` JNI DETECTED ERROR IN APPLICATION: use of invalid jobject 0x7bc4f3eb00 ```

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