"Application resources are created and stored within the Android project files under the /res directory. Using a well-defined but flexible directory structure, resources are organized, defined, and compiled with the application package. Application
resources are not shared with the rest of the Android system."
Storing Application Resources:
application resources together and compiling them into the application package has
the following benefits:
1 Code is cleaner and easier to read, leading to fewer bugs.
2. Resources are organized by type and guaranteed to be unique.
3.Resources are conveniently located for handset customization.
4.Localization and internationalization are straightforward.
The Android platform supports a variety of resource types (see Figure), which
can be combined to form different types of applications.
Android applications can include many different kinds of resources. The following
are some of the most common resource types:
Types of Resources:
1. Strings, colors, and dimensions
2. Drawable graphics files
3. Layout files
4. Raw files of all types
Fig - Resource Types in an Android Application
"Resource types are defined with special XML tags and organized into specially
named project directories. Some /res subdirectories, such as the /drawable,
/layout, and /values directories, are created by default when a new Android
project is created, while others must be added by the developer when required".
Resource files stored within /res subdirectories must abide by the following rules:
Rules for Naming of Resource Files:
1. Resource filenames must be lowercase.
2. Resource filenames may contain letters, numbers, underscores, and periods
only.
3. Resource filenames (and XML name attributes) must be unique.