Resources
1. Resources
Android supports that resources, like images and certain XML configuration files, can be keep separate from the source code.
These resources must be defined in the
res
directory in a special folder dependent on their purpose. You can also append additional qualifiers to the folder name to indicate that the related resources should be used for special configurations, e.g. you can specify that a resource is only valid for a certain screen size.The following table give an overview of the supported resources and their standard folder prefix.
The
gen
directory in an Android project contains generated values. R.java
is a generated class which contains references to certain resources of the project.If you create a new resource, the corresponding reference is automatically created in
R.java
via the Eclipse ADT tools. These references are static integer values and define IDs for the resources.The Android system provides methods to access the corresponding resource via these IDs.
For example to access a String with the
R.string.yourString
ID, you would use the getString(R.string.yourString))
method.R.java
is automatically created by the Eclipse development environment, manual changes are not necessary and will be overridden by the tooling.2. Assets
While the
res
directory contains structured values which are known to the Android platform, the assets
directory can be used to store any kind of data. You access this data via the AssetsManager
which you can access the getAssets()
method.AssetsManager
allows to read an assets as InputStream
with the open()
method.3. Defining IDs
Android allows that you define ID of user interface components dynamically in the layout files, via the
@+id/your_id
notation.To control your IDs you can also create a file called
ids.xml
in your /res/values
folder and define all IDs in this file.This allow you to use the ID directly in your layout file.
Related Topics : Android Development Tutorial (Based on Android 4.1) class-1
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