An app in android can be compiled separately.

An application in AndroidProgramYou can compile it separately. After compilation, You need to regenerate system. IMG and execute. Build in the source code directory. / Envsetup. Sh (. is followed by a space), there are more commands: - Croot: Changes directory to the top of the tree. - M: makes from the top of the tree. - MM: builds all of the modules in the current directory. - Mmm: builds all of the modules in the supplied directories. -Cgrep: greps on all local C/C ++ Files. - Jgrep: greps on all local java files. -Resgrep: greps on all local res/*  . XML files. -godir: Go to the directory containing a file. you can add-help to view usage. We can use Mmm to compile the module of the specified directory, for example, compile the contact: # Mmm packages/apps/contacts/or # Make contacts to generate two files after compilation: out/target/product/generic/data/APP/contactstests.apk out/target/product/generic/system/APP/contacts.apk you can use "make Snod" to regenerate the system. IMG re-run the simulator