In the application using the library, create a style which defines values for those attributes.Īpply that style as a theme for the application. Link to those attributes in the library's XML. Instead of putting the background in the code, you can create a color resource ( #FF0000) then reference that Going one level of abstraction higher is to create an attribute( ), which doesn't directly define the color but can be set by a style or theme (android:background='?style/red').Ī high-level layout of the solution looks like this:ĭefine attributes for what XML values you want to customize. Let's take the simple example of a background: the most direct way to set a background is directly in code (android:background='#FF0000'). Attributes are a tad under-documented, but with attributes, you can define references which are filled in later by styles.Īttributes are one level of abstraction beyond the normal use of XML references in Android. Chances are you've already worked with styles and themes before (if you haven't, you should read up on them), but attributes aren't commonly needed when you're working on a one-off application. The answer is to use attributes and styles/themes. You could try subclassing but using your own XML, but then you're tightly coupling your code to the library and will likely end up duplicating code. You could subclass the library's Activity and (in code) change the style, but then you miss out on all the advantages of resource qualifiers. In some cases, I'm even reusing entire Activities.īut this brings up a problem - how do you restyle an Activity in a library? Say you've got a custom date picker in your library which you want to customize to each application's look and feel. These libraries have proven very useful in my work because there's a lot of common code between applications.

It allows you to define multiple Android projects where (at build time) it combines them all into one. About nine months ago, Android added library support.

Custominzing android studio theme