Add App Resources
App resources such as
bitmaps and layouts are organized into type-specific directories inside each
module's res/ directory. You can also
add alternative versions of each file that are optimized for different device
configurations (such as a high-res version of a bitmap for high-density
screens).
Android Studio helps you
add new resources and alternative resources in several ways, depending on the
type of resource you want to add. This page describes how to add basic resource
files, how to change the location of your resources, and how resource merging
works.
Add an XML resource file
Although the pages linked above describe workflows that
are customized to each type of resource, you can add any XML resource file by
following these steps:
1.
Click the target app module in the Project window
(while in either the Android or Project view), and then select File
> New > Android resource file.
2.
Fill in the details in the dialog:
o File name: Type the name for the
XML file (does not require the .xml suffix).
o Resource type: Select the type of resource
you want to create.
o Root element: If applicable, select
the root XML element for the file. Some resource types support only one type of
root element, so depending on the type selected above, this might not be
editable.
o Directory name: The directory must be
named in a way that's specific to the resource type and configuration
qualifiers. So you should not edit this unless you want to add configuration
qualifiers to the directory name by hand (see Available qualifiers
instead).
o Available qualifiers: Instead of typing
configuration qualifiers for your layout directory, you can add them by
clicking a qualifier from the list on the left, and then clicking Add
.
.
3.
Once you've added all the qualifiers you want, click OK.
Tip: Right-click an existing
resource directory within the res folder and select New > type-name resource file. This opens a simplified
version of the New Resource File dialog that's specific to your desired
resource type.
Tip: Some complex resources
require multiple XML resource files. For example, an animated vector drawable
has a vector drawable object and an animation object, which requires at least
three XML files. You can keep the three separate XML files if you need to reuse
one or more of them. But, if the XML files are used only for this one animated
vector drawable, you can instead use the inline resource format provided in the
Android Asset Packaging Tool (AAPT). With AAPT, you can define all three
resources in one XML file. For more information, see Inline Complex XML Resources.
Add a resource directory
If you need to add a new resource directory, follow these
steps:
1.
Click the target app module in the Project window,
and then select File > New > Android resource directory.
o Directory name: The directory must be
named in a way that's specific to the resource type and combination of
configuration qualifiers. So you should not edit this unless you want to add
configuration qualifiers to the directory name by hand (use Available
qualifiers instead).
o Resource type: Select the type of
resource you want to create.
o Source set: Select the source set
where you want the layout.
o Available qualifiers: Instead of typing
configuration qualifiers for your layout directory, you can add them by
clicking a qualifier from the list on the left, and then clicking Add 
.
.
3.
Once you've added all the qualifiers you want, click OK.
Change your resource directory
By default, your resources are located in module-name/src/source-set-name/res/. For example, resources
for your module's main source set are in src/main/res/ and resources for the debug source set are
in src/debug/res/.
However, you can change
these paths to any other location (relative to the build.gradle file) with the res.srcDirs property in the sourceSets
{}
block. For example:
android {
sourceSets {
main {
res.srcDirs = ['resources/main']
}
debug {
res.srcDirs = ['resources/debug']
}
}
}
sourceSets {
main {
res.srcDirs = ['resources/main']
}
debug {
res.srcDirs = ['resources/debug']
}
}
}
You can also specify multiple
resource directories for one source set, and then the build tools will merge
them together. For example:
android {
sourceSets {
main {
res.srcDirs = ['res1', 'res2']
}
}
}
sourceSets {
main {
res.srcDirs = ['res1', 'res2']
}
}
}
Note: If two or more resource
directories contain the same resource file, an error occurs during resource merging.
Resource merging
Resources in your final APK file may come from 3
different sources:
·
The main source set (generally located in src/main/res/)
When all resources from
each source set or library are unique, they're all added into the final APK. A
resource is considered unique if it's file name is unique within both
its resource type directory and the resource qualifier (if defined).
If there exist two or
more matching versions of the same resource, then only one version is included
in the final APK. The build tools select which version to keep based on the
following priority order (highest priority on the left):
build variant > build
type > product flavor > main source set > library dependencies
For example, if the main
source set contains:
·
res/layout/foo.xml
·
res/layout-land/foo.xml
And the debug build type
contains:
·
res/layout/foo.xml
Then the final APK
includes res/layout/foo.xml from the debug build
type and res/layout-land/foo.xml from the main source
set.
However, if your build
configuration specifies multiple resource folders for a given source set
and there are conflicts between those sources, an error occurs and the merge fails
because each resource directory has the same priority.