i want to learn modify and compile source, what i need to learn,can you give some link or sample and so on, i know i also need to learn frameworks knowledge,how and where to learnAnswer1:
You can download the source from source.android.com and start doing things with it. Provided that you have a super system with monster resources, you can play with the source.
And regarding changes, so there are various things inside the source, like lots of XML files, lots of images, drawables.. Lots Java code and C code too. You might need to modify the drivers and the kernels too. There's only one compiled source of info, that is the android documentation itself, but is a little buggy. apart from this, you can ask google about the problems.
all in all, I didn't find any resource, during my work, that serves as the sole source of information. since you see lots of resources, so collective knowledge of all of them will help you in the end.
This area is still quite poorly documented. But things should be comprehensible, and understandable as you keep working with it.