TextView subclass that applies a customized font. You also need FontFactory class, available in the first comment of this gist

StyledTextView.java

import android.content.Context;
import android.graphics.Typeface;
import android.util.AttributeSet;
import android.widget.TextView;

public class StyledTextView extends TextView {
    private static final int NO_STYLE = -1;

    public StyledTextView(Context context) {
        super(context);
        style(null, NO_STYLE);
    }

    public StyledTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        style(attrs, NO_STYLE);
    }

    public StyledTextView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        style(attrs, defStyleAttr);
    }

    private void style(AttributeSet attrs, int defStyle) {
        if (isInEditMode())
            return;

        FontFactory factory = new FontFactory(getContext());
        int style = getTypeface() != null ? getTypeface().getStyle() : Typeface.NORMAL;

        Typeface tf = factory.getRegularTypeface();
        if (attrs != null) {


        }
        if (style == Typeface.BOLD)
            tf = factory.getBoldTypeface();
        else if (style == Typeface.ITALIC)
            tf = factory.getItalicTypeface();

        setTypeface(tf);
    }
}

import android.content.Context;
import android.graphics.Typeface;

public class FontFactory {
    protected static Typeface sTypefaceBold = null;
    protected static Typeface sTypefaceRegular = null;
    protected static Typeface sTypefaceLight = null;

    protected static final String FONTS_FOLDER = "fonts/";
    public static final String DEFAULT_BOLD_TYPEFACE_NAME = FONTS_FOLDER + "MyFont-Bold.ttf";
    public static final String DEFAULT_REGULAR_TYPEFACE_NAME = FONTS_FOLDER + "MyFont-Regular.ttf";
    public static final String DEFAULT_ITALIC_TYPEFACE_NAME = FONTS_FOLDER + "MyFont-Italic.ttf";
    private static FontFactory instance;

    Context context;

    public FontFactory(Context context) {
        this.context = context;
    }

    public Typeface getBoldTypeface() {
        if (sTypefaceBold == null) {
            sTypefaceBold = getTypeface(DEFAULT_BOLD_TYPEFACE_NAME, Typeface.BOLD);
        }
        return sTypefaceBold;
    }

    public Typeface getItalicTypeface() {
        if (sTypefaceLight == null) {
            sTypefaceLight = getTypeface(DEFAULT_ITALIC_TYPEFACE_NAME, Typeface.NORMAL);
        }
        return sTypefaceLight;
    }

    public Typeface getRegularTypeface() {
        if (sTypefaceRegular == null) {
            sTypefaceRegular = getTypeface(DEFAULT_REGULAR_TYPEFACE_NAME, Typeface.NORMAL);
        }
        return sTypefaceRegular;
    }

    public Typeface getTypeface(String resourceName, int defaultStyle) {
        return Typeface.createFromAsset(context.getAssets(), resourceName);
    }

    public Typeface getTypeface(int style) {
        if (style == Typeface.BOLD) {
            return getBoldTypeface();
        } else {
            return getRegularTypeface();
        }
    }

    public static FontFactory getInstance(Context context) {
        if (instance == null) {
            instance = new FontFactory(context);
        }
        return instance;
    }
}