In Android development if we want to set custom font to any Button or TextView then we need to do this programmatically.

There is some tricks to set fonts from xml i.e custom Views. 

There are steps to do that.

1. Create class with name CustomTextView and extends TextView.

2. Add required Constructors.

3. Go to values folder in res. and create attrs.xml file.

4. Write below code under resources tag.

<declare-styleable name="ViewCustom">
        <attr name="font" format="string" />
    </declare-styleable>

5. In CustomTextView class write below code in constructors.  where mFont is String variable.

TypedArray a = context.getTheme().obtainStyledAttributes(
                attrs,
                R.styleable.ViewCustom,
                0, 0);
        try {
            mFont = a.getString(R.styleable.ViewCustom_font);
        } finally {
            a.recycle();
        }

 if (mFont != null) {
            Typeface tf = Typeface.createFromAsset(context.getAssets(), "fonts/" + mFont);
            setTypeface(tf);
        }

6. Add fonts to assets/ fonts folder.

7. Replace TextView with you CustomTextView. like below:-

<com.example.CustomTextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    />

8.  Add font tag to CustomTextView like below :-

app:font="font_name"

Note:- font_name is name of font from assets/fonts folder.

9. Now Run your code and check font style.

Happy Coding!!