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

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

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

And 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> 

Then styles can be declared:

<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> 

You don't need any prefixes, it will work without them. This is code from one of my projects, which works just fine

<style name="defaultTriangle"> <item name="triangleColor">#FF33B5E5</item> <item name="triangleStrokeColor">@android:color/black</item> <item name="triangleStrokeWidth">3dp</item> </style> <si.kseneman.views.Triangle style="@style/defaultTriangle" android:layout_width="match_parent" android:layout_height="0dip" android:layout_weight="1" android:padding="10dp" android:rotation="0" /> 

I've done next for custom font CustomTextView

public class KlavikaTextView extends TextView { private final static int KLAVIKA_BOLD = 0; private final static int KLAVIKA_BOLD_ITALIC = 1; private final static int KLAVIKA_LIGHT = 2; private final static int KLAVIKA_LIGHT_ITALIC = 3; private final static int KLAVIKA_MEDIUM = 4; private final static int KLAVIKA_MEDIUM_ITALIC = 5; private final static int KLAVIKA_REGULAR = 6; private final static int KLAVIKA_REGULAR_ITALIC = 7; public KlavikaTextView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); parseAttributes(context, attrs); } public KlavikaTextView(Context context, AttributeSet attrs) { super(context, attrs); parseAttributes(context, attrs); } public KlavikaTextView(Context context) { super(context); } private void parseAttributes(Context context, AttributeSet attrs) { TypedArray values = context.obtainStyledAttributes(attrs, R.styleable.KlavikaTextView); // The value 0 is a default, but shouldn't ever be used since the attr is an enum int typeface = values.getInt(R.styleable.KlavikaTextView_typeface, KLAVIKA_REGULAR); // You can instantiate your typeface anywhere, I would suggest as a // singleton somewhere to avoid unnecessary copies switch (typeface) { case KLAVIKA_BOLD: setTypeface(App.klavikaBold); break; case KLAVIKA_BOLD_ITALIC: setTypeface(App.klavikaBoldItalic); break; case KLAVIKA_LIGHT: setTypeface(App.klavikaLight); break; case KLAVIKA_LIGHT_ITALIC: setTypeface(App.klavikaLightItalic); break; case KLAVIKA_MEDIUM: setTypeface(App.klavikaMedium); break; case KLAVIKA_MEDIUM_ITALIC: setTypeface(App.klavikaMediumItalic); break; case KLAVIKA_REGULAR_ITALIC: setTypeface(App.klavikaRegularItalic); break; case KLAVIKA_REGULAR: default: setTypeface(App.klavikaRegular); break; } }} 

Then in values I've created attr.xml

 <!-- Define the values for the attribute --> <attr name="typeface" format="enum"> <enum name="klavika_bold" value="0" /> <enum name="klavika_bold_italic" value="1" /> <enum name="klavika_light" value="2" /> <enum name="klavika_light_italic" value="3" /> <enum name="klavika_medium" value="4" /> <enum name="klavika_medium_italic" value="5" /> <enum name="klavika_regular" value="6" /> <enum name="klavika_regular_italic" value="7" /> </attr> <!-- Tell Android that the class "KlavikaTextView" can be styled, and which attributes it supports--> <declare-styleable name="KlavikaTextView"> <attr name="typeface" /> </declare-styleable> 

Next created the style

 <style name="TextView.Example"> <item name="typeface">klavika_bold</item> </style> 

This style you can use for your xml Layouts

style="@style/TextView.Example" 

<?xml version="1.0" encoding="utf-8"?> <resources xmlns:android="http://schemas.android.com/apk/res/android" xmlns:custom="http://schemas.android.com/apk/res/com.my.project"> <style name="my_style"> <item name="custom:tag">some_value</item> </style> </resources> 

you are trying to apply XML namespacing to an attribute value, which won't work. In this case, you should specify the package name directly, like this:

 <style name="my_style"> <item name="com.my.project:tag">some_value</item> </style> 

Fast solution via code!

 String pathFont = "fonts/ReallyCoolFont.ttf"; TextView text = (TextView) findViewById(R.id.TextView1); Typeface fontFace = Typeface.createFromAsset( getAssets(), pathFont ); text.setTypeface( fontFace ); 

Third-party libraries , solve the problem, in XML!

1 - https://github.com/leok7v/android-textview-custom-fonts

2 - https://github.com/ragunathjawahar/android-typeface-textview

My suggestion

You will have other needs, and for each component you will have to customize a class.

Another problem you have other layouts and N TextView components for maintenance you will have a lot of work .

I use this method in projects in the OnCreate of my activity if I need to change the font I have to do this only in the OnCreate method of each activity .

 private static final String FONT = "ReallyCoolFont.ttf"; public static void allTextView(final Context context, final View root) { String fontPath = FONT; try { if (root instanceof ViewGroup) { ViewGroup viewGroup = (ViewGroup) root; int childCount = viewGroup.getChildCount(); for (int i = 0; i < childCount; i++) allTextView(context, viewGroup.getChildAt(i) ); } else if (root instanceof TextView) ((TextView) root).setTypeface(Typeface.createFromAsset(context.getAssets(), fontPath)); } catch (Exception e) { e.printStackTrace(); } } // call in OnCreate Activity allTextView(this, findViewById(R.layout.main) ); 

The custom attributes are defined using <declare-styleable> tags; usually the file is called attrs.xml. The namespace declaration will have your app's package name in it.

The whole process is described here: Creating a View Class | Android Developers