Android: How to custom-declare XML namespace in styles.xml?

1) you need to define an attribute for your fonts in attr.xml file in res folder:

<attr name="myfonts" format="string"></attr>

2) you need to define custom style for your TextView and here we use our defined attribute(myfonts):

<declare-styleable name="MyCustomStyle">    <attr name="myfonts" /></declare-styleable>

3)

<style name="CoolTextView">    <item name="myfonts">ReallyCoolFont.ttf</item></style>

summary of what you have so far:

<?xml version="1.0" encoding="utf-8"?><resources>    <attr name="myfonts" format="string">    </attr>    <declare-styleable name="MyCustomStyle">        <attr name="myfonts" />    </declare-styleable>     <style name="CoolTextView">        <item name="myfonts">ReallyCoolFont.ttf</item>    </style></resources> 

4)Now your layout would be:

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    android:layout_width="match_parent"    android:layout_height="match_parent" >    <com.example.MyCustomTextView        android:id="@+id/result"        style="@style/CoolTextView"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerInParent="true"        android:text="HELLO WORLD!"        android:textSize="24dp"        android:gravity="center" >    </com.example.MyCustomTextView></RelativeLayout>

5)and your MyCustomTextView is:

public class MyCustomTextView extends TextView {    private static final String TAG = "TextView";    public MyCustomTextView(Context context) {        super(context);    }    public MyCustomTextView(Context context, AttributeSet attrs) {        super(context, attrs);        settingFont(context, attrs);    }    public MyCustomTextView(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);        settingFont(context, attrs);    }    private void settingFont(Context ctx, AttributeSet attrs) {        TypedArray a = ctx.obtainStyledAttributes(attrs, R.styleable.MyCustomStyle);        String customFont = a.getString(R.styleable.MyCustomStyle_myfonts);        Typeface tf = null;        try {        tf = Typeface.createFromAsset(ctx.getAssets(), customFont);          } catch (Exception e) {            Log.e(TAG,e.getMessage());            a.recycle();            return;        }        setTypeface(tf);          a.recycle();    }}

I assumed you put the font in asset not in asset/fonts directory.

also I highly recommend read this.

You don't need to add any prefix to reference your custom attributes in the style resource files. Doing it like this will work just fine:

<style name="CoolTextView">    <item name="customFont">ReallyCoolFont.ttf</item></style>

The answer is to NOT specify the namespace in the style.

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