Android: Why Parcel?

Question

I'm a C/C++ guy, and I'm quite new to Java and Android. So I'm creating a class instance in Activity "A" and I'm trying to use this instance to Activity "B". In C/C++ you would simply pass the address (pointer) of the instance. Now I learned that with Android I should use a Parcel, but I don't get the idea: why would I want do all that parceling/deparceling procedure when all I want to do is passing a pointer? Please enlighten me!

Answer 1

This is related to the Android activity model.

Since your app may be killed by the system to recover RAM (this should only happen when it's in the background, unless the system is in a really bad situation), an object reference just won't do. It'd be completely worthless once your process dies.

The intent you use to start activities is saved by the Activity Manager, so that it can be used to recreate your activity when the user navigates back to it. That's why all the data in your intent has to be parceled.

Keep in mind that this means that your two activities will have two similar instances -- but naturally, they will not be the same object, so changes to one won't be reflected in the other.