Hello everyone ! Hope your projects are doing well !
We are currently working on a mobile game, and I’m starting to implement platform related logic (notification, ads, in-app purchases).
For now, I managed to implement ads with a plugin, and basic notification with Unreal BlueprintPlatformLibrary. But I’m not satisfied, my current quest on implementing this notification left a void in my heart, a missing piece in my UnrealLearningAdvendurePuzzle™.
How Unreal link C++ and Java logic ?
How can I implement my own Java logic if I need to do some modification / update ?
I have found multiple clues to resolve these mysteries:
- The Beginning,
AndroidJNI.cpp.
It’s where my knowledge lead me, the last function of c++, and the first I don’t fully understand.
int32 AndroidThunkCpp_ScheduleLocalNotificationAtTime(const FDateTime& FireDateTime, bool LocalTime, const FText& Title, const FText& Body, const FText& Action, const FString& ActivationEvent)
{
//Convert FireDateTime to yyyy-MM-dd HH:mm:ss in order to pass to java
FString FireDateTimeFormatted = FString::FromInt(FireDateTime.GetYear()) + "-" + FString::FromInt(FireDateTime.GetMonth()) + "-" + FString::FromInt(FireDateTime.GetDay()) + " " + FString::FromInt(FireDateTime.GetHour()) + ":" + FString::FromInt(FireDateTime.GetMinute()) + ":" + FString::FromInt(FireDateTime.GetSecond());
JNIEnv* Env = FAndroidApplication::GetJavaEnv();
if (Env != NULL)
{
auto jFireDateTime = FJavaHelper::ToJavaString(Env, FireDateTimeFormatted);
auto jTitle = FJavaHelper::ToJavaString(Env, Title.ToString());
auto jBody = FJavaHelper::ToJavaString(Env, Body.ToString());
auto jAction = FJavaHelper::ToJavaString(Env, Action.ToString());
auto jActivationEvent = FJavaHelper::ToJavaString(Env, ActivationEvent);
return FJavaWrapper::CallIntMethod(Env, FJavaWrapper::GameActivityThis, FJavaWrapper::AndroidThunkJava_LocalNotificationScheduleAtTime, *jFireDateTime, LocalTime, *jTitle, *jBody, *jAction, *jActivationEvent);
}
return -1;
}
I found the word JNI a lot of time, and if I’m correct, it’s an interface to link C++ and Java, but I’m not sure, and I don’t understand how.
- The End,
LocalNotificationReceiver.java.
I’m sorry if I’m wide of the mark, Java is not my first language. But it seems like here are the good stuff, I can found the notification builder just like in the Android documentation.
NotificationCompat.Builder builder = new NotificationCompat.Builder(context, NOTIFICATION_CHANNEL_ID)
.setSmallIcon(notificationIconID)
.setContentIntent(pendingNotificationIntent)
.setWhen(System.currentTimeMillis())
.setTicker(details) // note: will not show up on Lollipop up except for accessibility
.setContentTitle(title)
.setStyle(new NotificationCompat.BigTextStyle().bigText(details));
if (android.os.Build.VERSION.SDK_INT >= 21)
{
builder.setContentText(details);
builder.setColor(0xff0e1e43);
}
But the file is located ProjectName\Intermediate\Android\arm64\src\com\epicgames\unreal\LocalNotificationReceiver.java
And in the Engine it’s
Engine/Build/Android/Java/src/com/epicgames/unreal/LocalNotificationReceiver.java
So where this file come from ? Can I modify the file in the engine without risk ? Does it woks the same for IOS (This one scars me) ?
If you have some knowledge to share, some documentation in this subject, I would love to hear about it.