[Android] Please predecessors under the expert guidance of new

When I first came internship , the company 's older brother gave me a cell phone company to do system source code, let me change Mms, Contacts app several modules .
now facing tens of thousands of lines of code, plus a small function do not know how to start.
In addition to ask my colleagues to ask , what is the book in this regard , in this respect refers to the system's own app source code analysis .
I now want to add a button to the contact list entries , but for a long time , xml layout did not find , estimated to be written in java . . .
seek help.
------ Solution ---------------------------------------- ----
see documentation to see the screen design, these should have it
------ Solution --------------------- -----------------------
this has layout yet. . I just graduated this practice also allows to change , so that added a check box in the contacts , the landlord will be able to find the next track with Degbug , Eclipse global search for the information you see , a little bit of track , definitely find !
------ Solution ---------------------------------------- ----
you still be familiar with the source architecture android system , and then deep right, if we direct that the overall depth on the whole mess !
------ Solution ---------------------------------------- ----
" now I want to add a button to the contact list entries , but for a long time , xml layout did not find , estimated to be written in java .. ."
---- good, not xml layout , but dynamically generated code , you'll see this file : ContactListItemView.java
------ eference --------- ------------------------------

has been changing for the better , which is reserved showCallButton this method