Where can I find Android source code online?
Everything is mirrored on omapzoom.org. Some of the code is also mirrored on github.
Contacts is here for example.
Since December 2019, you can use the new official public code search tool for AOSP: cs.android.com. There's also the Android official source browser (based on Gitiles) has a web view of many of the different parts that make up android. Some of the projects (such as Kernel) have been removed and it now only points you to clonable git repositories.
To get all the code locally, you can use the repo helper program, or you can just clone individual repositories.
And others:
- Downloading the Source Tree
2020: The official AOSP code search https://cs.android.com/
You can view the source code through http://developer.android.com, when you're reading the API there will be a link to the matching source code on GitHub, you just need to add the Android SDK Reference Search Plugin on Chrome.
I blogged about it here:
http://blog.blundellapps.com/add-source-code-links-to-android-apis/
I stumbled across Android XRef the other day and found it useful, especially since it is backed by OpenGrok which offers insanely awesome and blindingly fast search.