Override fonts application wide in android.

TypefaceUtil.java

package com.blogspot.ramannanda.apps.simplyread.utils;

import android.content.Context;
import android.graphics.Typeface;
import android.renderscript.Font;
import android.util.Log;

import java.lang.reflect.Field;

public class TypefaceUtil {
    private static final String tag=TypefaceUtil.class.getName();
    /**
     * Using reflection to override default typeface
     * In case you want to use default font just pass true to the method
     * NOTICE: DO NOT FORGET TO SET TYPEFACE FOR APP THEME AS DEFAULT TYPEFACE WHICH WILL BE OVERRIDDEN
     * @param context to work with assets
     * @param defaultFontNameToOverride for example "monospace"
     * @param customFontFileNameInAssets file name of the font from assets
     */
    public static Typeface overrideFont(Context context, String defaultFontNameToOverride, String customFontFileNameInAssets, boolean isDefault) {
        Typeface customFontTypeface=null;
        try {

            if(isDefault){
                customFontTypeface = Typeface.create((Typeface)null,Typeface.NORMAL);
            }
            else{
               customFontTypeface= Typeface.createFromAsset (context.getAssets(), customFontFileNameInAssets);
            }

            final Field defaultFontTypefaceField = Typeface.class.getDeclaredField(defaultFontNameToOverride);
            defaultFontTypefaceField.setAccessible(true);
            defaultFontTypefaceField.set(null, customFontTypeface);

        } catch (Exception e) {
            Log.e(tag,"Can not set custom font " + customFontFileNameInAssets + " instead of " + defaultFontNameToOverride,e);
        }
        return customFontTypeface;
    }
}