how to compile apk in android

Open the Android.mk of your apk then find the 

LOCAL_PACKAGE_NAME := Settings

or

LOCAL_MODULE := 

then come the back to android base folder 

$make Settings

Apk will be generated in out folder

If apk is your properitery then install it with 

adb install -r  xyz.apk

if the apk belongs to android base code

then 

adb root

adb remount

adb push xyz.apk /system/app/