Using theme references in XML drawables requires API level 21

问题:

Is there a way to make following code compatible with lower API levels:

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">      <item android:drawable="?android:attr/selectableItemBackground"/>      <item android:gravity="bottom">         <shape android:shape="rectangle">             <size android:height="1px"/>             <solid android:color="#ccc"/>         </shape>     </item>  </layer-list> 

The part: android:drawable="?android:attr/selectableItemBackground" produces this message:

Using theme references in XML drawables requires API level 21 (current min is 15)

回答1:

Create an attars.xml file under the values folder.

In the attars.xml file, create an item for selectableItemBackground:

<?xml version="1.0" encoding="utf-8"?> <resources>     <attr name="selectableItemBackground" format="reference" /> </resources> 

In your styles.xml define this attribute with your drawable:

<item name="selectableItemBackground">@drawable/yourDrawable</item> 

And then in your drawable file, reference the attribute:

<item android:drawable="?attr/selectableItemBackground"/> 

回答2:

use android:drawable="?attr/selectableItemBackground"

文章来源: Using theme references in XML drawables requires API level 21