New projects should follow the Android Gradle project structure that is defined on the Android Gradle plugin user guide.
Class names are written in UpperCamelCase.
For classes that extend an Android component, the name of the class should end with the name of the component; for example: SignInActivity, SignInFragment, ImageUploaderService, ChangePasswordDialog.
Resources file names are written in lowercase_underscore.
Naming conventions for drawables:
| Asset Type | Prefix | Example |
|---|---|---|
| Background | bg_ |
bg_screen1.9.png |
| Icon | ic_ |
ic_star_black_24dp.png |
| Image | img_ |
img_star_48x32dp.png |
All icons should follow ic_{{name}}_{{color}}_{{size}}dp. See Material Icons Guide.
Note: Occasionally color won't be applicable, in which case don't include it. If the resource isn't square, provide the widthxheight.
Naming conventions for selector states:
| State | Suffix | Example |
|---|---|---|
| Normal | _normal |
btn_order_normal.9.png |
| Pressed | _pressed |
btn_order_pressed.9.png |
| Focused | _focused |
btn_order_focused.9.png |
| Disabled | _disabled |
btn_order_disabled.9.png |
| Selected | _selected |
btn_order_selected.9.png |
Layout files should match the name of the Android components that they are intended for but moving the top level component name to the beginning. For example, if we are creating a layout for the SignInActivity, the name of the layout file should be activity_sign_in.xml.
| Component | Class Name | Layout Name |
|---|---|---|
| Activity | UserProfileActivity |
activity_user_profile.xml |
| Activity Content | UserProfileActivity |
content_user_profile.xml |
| Fragment | SignUpFragment |
fragment_sign_up.xml |
| Dialog | ChangePasswordDialog |
dialog_change_password.xml |
| AdapterView item | --- | item_person.xml |
| Partial layout | --- | partial_stats_bar.xml |
Note that Activity refers to the layout for the activity which will include the appbar, any view that overlays the main content and the content container.
A slightly different case is when we are creating a layout that is going to be inflated by an Adapter, e.g to populate a ListView. In this case, the name of the layout should start with item_.
Note that there are cases where these rules will not be possible to apply. For example, when creating layout files that are intended to be part of other layouts. In this case you should use the prefix partial_.
Similar to layout files, menu files should match the name of the component. For example, if we are defining a menu file that is going to be used in the UserActivity, then the name of the file should be activity_user.xml
A good practice is to not include the word menu as part of the name because these files are already located in the menu directory.
Resource files in the values folder should be plural, e.g. strings.xml, styles.xml, colors.xml, dimens.xml, attrs.xml
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