Where to get detail description on understanding android

I found lots of books on android which give basic concept on android Example (calling Activity, Intent, service, broadcast receivers etc). But I want to know brief description on all these concept. in os level or in api level how does it work. Also how connection with wifi or 3g works in api level.

I want to know brief understanding on android. Can anyone suggest an开发者_开发问答y tutorial or book to get detail understanding on android.

Thanks

Start with the Android Developer's Guide. http://developer.android.com/guide/index.html

I would recommend to buy a book. For me Professional Android 2 Application Development was really good. But probably now there is better (up to date) alternative.

Anyway I find reading books much easier starter than separate tutorials and articles.

If you want a really detailed view, just look at the source code.