Grouping Resource Types
You should place each type of resource in a specific subdirectory of your project's res/ directory. For example, here's the file hierarchy for a simple project:
MyProject/
src/
MyActivity.java
res/
drawable/
icon.png
layout/
main.xml
info.xml
values/
strings.xml
As you can see in this example, the res/ directory contains all the resources (in subdirectories): an image resource, two layout resources, and a string resource file. The resource directory names are important and are described in table 1.