Question

I have the following theme in res/values/styles.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources xmlns:android="http://schemas.android.com/apk/res/android">
    <style name="AppBaseTheme" parent="@android:style/Theme.NoTitleBar">
    </style>

    <style name="AppTheme" parent="AppBaseTheme">
        <item name="android:windowNoTitle">true</item>
    </style>
</resources>

If I remove the <item name="android:windowNoTitle">true</item> line, my activities have the titlebar on them. However, if I keep that line there, then they do not have a titlebar (which is what I want).

I’m curious why parent="@android:style/Theme.NoTitleBar" seems to have no effect? Does parent not do what I think it does? I thought it worked like this:

@android:style/Theme.NoTitleBar --> AppBaseTheme --> AppTheme
^                                   ^                ^
|                                   |                |
|                                   |                Has everything AppBaseTheme
|                                   |                does, unless it's overridden
|                                   |
|                                   Has everything @android:style/Theme.NoTitleBar
|                                   does, unless it's overridden (which I'm not
|                                   doing)
|
Sets whatever it needs to to not have a title, which I assume
is done by setting <item name="android:windowNoTitle">true</item>

However, I’ve also found that if I set <item name="android:windowNoTitle">true</item> in AppBaseTheme it also has no effect; I have to set it in AppTheme. Then what the heck is the point of specifying the parent?

Answer 1

I think I just figured it out. It turns out that when I created the project, Android created a res/values-14/styles.xml file, and inside of that was <style name="AppBaseTheme" parent="android:Theme.Holo.Light.DarkActionBar">.

It turns out that the res/values-14/styles.xml file was overriding my default res/values/styles.xml because the device I was testing on has API level 14, and thus it preferred the files in values-14 than the default values.

Inheritance does seem to work like I thought it did; I just wasn’t realizing things were being overridden by the files created when I first made my project.