Compiled and uncompiled resources in Android

Question

During the build of Android application some resources files are compiled and put in a binary file (resources.arsc) and some other not. In the book "Beginning Android 4" I've found the following phrase: "The .apk file is a ZIP archive containing the .dex file, the compiled edition of your resources (resources.arsc), any uncompiled resources (such as what you put in res/raw/), and the AndroidManifest.xml file." However, after examining several apk files I've found that usually layout files are not put into resources.arsc and sometime other xml files from resources folder are also left untouched.
Could someone clarify me which resources are called compiled and which are not and also when they are compiled, under which circumstances?

Answer 1

Which resources do you think are not compiled? All Android resources are compiled -- the only usable representation of them is as the binary resources.arsc format. Traditional Java resources are not compiled, but we generally dont use those in Android. (There is probably a place or two that does use them, though.)