[shortstuffsushi]

You make it sound like it is as simple as that, only a method table instead of a header field :)

That said, you mention using a varint or uint32 which "use more CPU or memory" -- 16 bits vs 32 bits in applications that use megabytes seems trivial. Can you explain why that's a concern?

[kuschku]

It's not a concern anymore, but when Android was created, the average application was less than 20kiB. Back then, resource restrictions were a lot more problematic.