Custom attributes in styles.xml

I have created a custom widget, and I'm declaring it in layout.xml. I have also added some custom attributes in attr.xml. However, when trying to declare these attributes in a style in styles.xml, it's giving me No resource found that matches the given name: attr 'custom:attribute'.

I have put the xmlns:custom="http://schemas.android.com/apk/res/com.my.package" in all of the tags in styles.xml, including <?xml>, <resources>, and <style>, but it still gives me the same error, that it can't find my custom XML namespace.

I can, however, use my namespace to manually assign attributes to the view in my layout.xml, so there is nothing wrong with the namespace. My issue lies in making styles.xml aware of my attr.xml.

I figured it out! The answer is to NOT specify the namespace in the style.

<?xml version="1.0" encoding="utf-8" ?>
<resources xmlns:android="http://schemas.android.com/apk/res/android">
    <style name="CustomStyle">
        <item name="android:layout_width">wrap_content</item>
        <item name="android:layout_height">wrap_content</item>

        <item name="custom_attr">value</item> <!-- tee hee -->
    </style>
</resources>

above answer is worked for me, I tried a litte change, I declare styleable for a class in resources element.

<declare-styleable name="VerticalView">
    <attr name="textSize" format="dimension" />
    <attr name="textColor" format="color" />
    <attr name="textBold" format="boolean" />
</declare-styleable>

in declare-styleable, the name attribute referenced a class name, so I had a view class call "com.my.package.name.VerticalView", it represented this declare must be use in VerticalView or subclasses of VerticalView. so we can declare style like this :

<resources>
    <style name="verticalViewStyle">
        <item name="android:layout_width">match_parent</item>
        <item name="android:layout_height">36dip</item>

        <item name="textSize">28sp</item>  <!-- not namespace prefix -->
        <item name="textColor">#ff666666</item>
        <item name="textBold">true</item>
    </style>
</resources>

that's why we didn't declare namespace at resources element, it still work.