初始化字型

private Typeface myFont;

// A good practice might be to call this in onCreate() of a custom
// Application class and pass 'this' as Context. Your font will be ready to use
// as long as your app lives
public void initFont(Context context) {
    myFont = Typeface.createFromAsset(context.getAssets(), "fonts/Roboto-Light.ttf");
}