How does inheritance behave when a style has both a parent attribute and a dotted name?

Question

According to the Android API Guide Styles and Themes, a style can inherit from another in two different ways:

• It can have a parent attribute:

  The parent attribute in the <style> element lets you specify a style from which your style should inherit attributes. You can use this to inherit attributes from an existing style and define only the attributes that you want to change or add.

• It can have a dotted name, as long as the style being inherited from is one "you've defined yourself":

  If you want to inherit from styles that you've defined yourself, you don't have to use the parent. Instead, you can use dot notation by prefixing the name of the style you want to inherit to the name of your new style, separated by a period.

What happens if a <style> has both a parent and a dotted name? For example, if I have:

 <style name="Foo.Bar.Baz" parent="Pen.Pinapple.Apple.Pen">

Does Foo.Bar.Baz inherit from both Foo.Bar and Pen.Pinapple.Apple.Pen? If an attribute is set in both Foo.Bar and Pen.Pinapple.Apple.Pen, which value will it get in Foo.Bar.Baz? What about other cases, like an attribute being set in Pen.Pineapple but also being set in the parent of Foo.Bar? Exactly what are the cascading rules, and where are they documented?

Answer 1

If you specify both, the parent attribute completely overrules the "dotted parent" (i.e., anything defined in the dotted parent is ignored).

In this example, MyStyle2.SubStyle will inherit the text color attribute from MyStyle1 and completely ignore the text size attribute from MyStyle2:

<style name="MyStyle1">
    <item name="android:textColor">#00f</item>
</style>

<style name="MyStyle2">
    <item name="android:textSize">18sp</item>
</style>

<style name="MyStyle2.SubStyle" parent="MyStyle1">
    <item name="android:textStyle">bold</item>
</style>