Is it possible to use Android 4 features on older versions?

Question

Since Android 4 has some nice new APIs, and since Android is Open Source, I've thought, Why not, for the time being, use the new APIs as if they are a part of the application, and when the time is right (when most users use the new version), use the official APIs instead?

For example, I think that the GridLayout, and maybe other new stuff, could be imported into projects.

My question is: Has anyone done such a thing? and if so, How well does it perform? Also, if anyone has done it, please publish a project, so that everyone could enjoy it.

I also wonder why Google doesn't provide such a mechanism in order to give more power to old versions and also to get rid of deprecated things.

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google does have some support for features of newer versions. for gridlayout , it's possible to use something like on this example: http://code.google.com/p/android-playground/source/checkout

for actionbar and fragments , there is the support library and there is the actionbarsherlock which is based on it (not created by google, but very good and even better ).

Answer 1

There are a few backports of new features to older devices available. The most prominent one are probably the Fragments from Honeycomb. Also this "slide to change tab" (ViwewPager) feature of e.g. Google+ app is available in such a compatibility library.

See e.g. the v13 lib and here

Answer 2

I also wonder why google doesn't provide such a mechanism in order to give more power to old versions

They do

Also, though it is technically possible to extract one component from one of the newer APIs and implement it at the application level in one of the older versions. I think you'll find that it is harder than it may seem. Using the compatibility library that they provide is probably your best bet.

when most users use the new version

The vast majority of devices that have made contact with the market in the last 2 weeks are on versions 7 - 10

see here for a breakdown of what versions are in use.