AddUObject when function takes bool?

Development Programming & Scripting C++
1

Hey i am trying to get call back functions from java to work (GameActivity.java).

I have been able to successfully do this when the callback takes no parameters but cannot figure out the correct way to define it when the function returns a bool.

GameActivity.java


public native void nativeMyCallbackFunc(boolean myReturnVal);

AndroidJNI.h


DECLARE_MULTICAST_DELEGATE_OneParam(FOnMyCallbackFunc, jboolean);
class FJavaWrapper
{
.....
static FOnMyCallbackFunc OnMyCallbackFunc;

AndroidJNI.cpp



FOnMyCallbackFunc JavaWrapper::OnMyCallbackFunc;

.....

extern "C" void Java_com_epicgames_ue4_GameActivity_nativeMyCallbackFunc(jboolean myReturnVal)
{
	FJavaWrapper::OnMyCallbackFunc.Broadcast(myReturnVal);
}

MyActor.h



	UFUNCTION(BlueprintNativeEvent, Category = "MyEvents")
	void OnMycallbackFunc(bool myReturnVal);

	void OnMycallbackFunc_Implementation(bool myReturnVal);

MyActor.cpp



void AMyActor::BeginPlay()
{
.....
FJavaWrapper::OnMyCallbackFunc.AddUObject(this, &AMyActor::OnMycallbackFunc);
}

It doesn’t like the AddUObject part and i think it is to do with the bool but i’m not sure how to define it as if i do a function callback with no paramaters using



DECLARE_MULTICAST_DELEGATE(FMycallbackFunc);

and AddUObject as above it works and fires off when used in blueprint.

Thanks

2

If you need to have a return value or any output parameters, you can’t use a multicast delegate. Multicasts can be bound to multiple callbacks simultaneously, so it doesn’t make sense to have return values.
Try declaring it with DECLARE_DELEGATE instead.

Also, I don’t know much about java and if it passes booleans by reference by default, but in C++ if you want to pass the value back to the caller, it needs to be either a return value, or a reference parameter.

3

your delegate is declared to take jboolean while OnMycallbackFunc takes bool, try and convert one way or the other so they are the same

4

Thanks man changed my declare to take a bool and cast the jboolean. All is working now.