Android Studio

Android Studio – Integrate APK Expansion Files

This article intents to clarify the process of integration of the Android APK Expansion Library with Android Studio.

Following the original documentation on how to integrate the Android APK Expansion library, and wasting time to investigate why the explained steps don’t work, provoked us to write this article.


In this example we are using the following versions:

Android Studio:  2.2 RC
Android SDK Platform: 24

I. Pre requires and file locations

First, you need to install the Android SDK

To integrate APK Expansion library, you need to import 3 libraries from your local Android SDK:

  1. play_licensing/library
  2. downloader_library
  3. zip_file
Required Libraries

The libraries are located in:


II. Import Libraries in Android Studio

Before you begin, you need to change the following line in the Android SDK downloader_library file:

Change line

Since the downloader_library depends on the play_licensing library, we must change the reference parameter to point to the correct directory.

Obviously, Android SDK has changed the name of the play_licensing library on some point without changing the reference in the properties file.

Now you can import the required libraries in your Android Studio IDE:

Open Android Studio (and your project respectively) and click on Import Module… ( File -> New -> Import Module… )

Import new module menu

Then, from the open window, type the path to the library you want to import. E.g:


Then click Next and leave all check-boxes as are. Then finish the operation.

Hint: If you import the downloader library first, the licensing library will be imported automatically  as well.

Repeat this step for zip_file library as well.

New Module window

Now, the Android APK Expansion library should be imported correctly.

In your project, the imported libraries should appears like this:

Imported modules

Next: Do not forget to add these libraries in your project dependencies:

Add module dependencies

III. Additional issues

In case your build failed with some of the following exceptions

Error:(23, 23) error: cannot find symbol class Header

Add in your file (including these of the libraries), the following line:

useLibrary 'org.apache.http.legacy'

This line must be added in android {….} block. E.g:

android {
    compileSdkVersion 24
    buildToolsVersion '24.0.1'
    useLibrary  'org.apache.http.legacy'

Also, copy org.apache.http.legacy.jar in your apps lib folder. This file is located in:

/your SDK directory/platforms/android-XX/optional/org.apache.http.legacy.jar

Then, add this file as a library (right click on the jar file -> Add as library)

Putting org.apache.http.legacy.jar in your local lib folder causes Multiple dex files define exception when building your app.

Error: java.lang.IllegalArgumentException: Service Intent must be explicit: Intent { }

This is a known bug.
In change from this:

boolean bindResult = mContext.bindService(new Intent(new String(Base64.decode("Y29tLmFuZHJvaWQudmVuZGluZy5saWNlbnNpbmcuSUxpY2Vuc2luZ1NlcnZpY2U="))),
                                          this, // ServiceConnection.

to this:

boolean bindResult = mContext.bindService(new Intent(new String(Base64.decode("Y29tLmFuZHJvaWQudmVuZGluZy5saWNlbnNpbmcuSUxpY2Vuc2luZ1NlcnZpY2U=")))
                                    this, // ServiceConnection.

We are not going to dive into the usage/functionality of these libraries.

Details about how to integrate and use the APK Expansion Library, you can find in the original Google Android Development documentation.

Your Comments are Welcome!


6 Best Free Photoshop extensions for Web Designers

These Photoshop extensions are cute and useful for web designers. refers to a design principle in which design cues are taken from the physical world.

skeuomorphism-it photoshop is a free Photoshop extension, by Roy Barber which turns skeuomorphism design to flat design. If you find anything skeuomorphic (icon, background or website templates) that you want to turn flat, this is the plugin to get.

This simple Photoshop plugin transforms your designs in seconds. Using it you can change a skeumorphism design into a flat design.  You can use it if you have skeuomorphic website templates, icons and etc. that want to turn flat.

There are already lots of online collection of free beautiful skeuomorphic Photoshop goodies that you can use directly.




GuideGuide is a free plugin for dealing with grids in Photoshop.

guide guide photoshop

Using GuideGuide you are able to create accurate columns, rows, midpoints and baselines. The extension makes you work with grids in Photoshop extremely easy.

If you need to design a site with multiple columns and gutters the GuideGuide extension is right for you.



The largest database of free vector icons available in PNG, SVG, EPS, PSD and BASE 64 formats.

Flaticon Photoshop

You can use Flaticon plugin to find the icons you need for your design, without leaving your work enviroment. These icons are scalable, editable and accessible to any screen reader.



Breezy is a free photoshop extension that export multiple layers.

Breezy Photoshop

Using Breeezy extension you will have the ability to export multiple graphic elements from your PSD. this added Photoshop functionality makes it extremely fast to prepare the graphic files for apps development, websites or flash banners.



Cut and Slice Me

Cut&Slice Me is a Photoshop extension for simplifying the process of cutting and slicing design.

Cut and Slice Photoshop

The Cut&Slide Me extension enables you to export the assets to different devices (Android, iPhone, Desktop) for designing. The exported files could have various scales and resolutions (retina for iPhone or HDPI, LDPI, MDPI and XHDPI for Android).

Another important photoshop extension is Cut and Slice Me. This plugin enables you to export the assets to different devices for designing and within a span of time.




CSS3Ps – free cloud based photoshop plugin that converts your layers to CSS3.

css3ps photoshop

CSS3Ps calculations are made in the cloud, so no need to update the plugin to use new features.  This plugin also supports multiple layers, prefixes, also SCSS and SASS for compass as well.




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Google Analytics

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Google local business

It is about the social aspect of search. This is the place you can connect with customers and industry representatives by adding them in your circles. Also they are available to add you in their cyrcles. Those who have your company in their circles will be able to see updates from your company. You can control of this information as well as updating your feed as you wish.


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SEO Digger

This is a free online tool that helps you optimize your site for Google. With SEO Digger, you can find your competitor’s best keywords and to see top 20 Google rankings of your site.


AdCenter Keyword Mutation Tool

The tool is siutable if you want to do both SEO and PPC optimization. Usng it uou can find keywords that have unique spellings and typos, so you can optimize your website.


SEO Book’s Firefox Plugin

Free Firefox extension to help you expand your browsers to become an SEO research guru.


Yammer Analytics

Yammer is a private social network that helps employees collaborate across departments, locations, and business apps. You can monitor your Yammer using: keyword monitoring, security settings, data export, data retention, and analytics.

Комплексен модел за оценка и прогноза на ВЕИ потенциала

Резюме: В доклада са представени данни и оценки относно приложимостта на комплексен модел за оценка на енергийния потенциал на ВЕИ. Направени са сравнителен анализ между конвенционални и възобновяеми технологии и оценка на пазарното проникване на възобновяемите технологии, както и прогнозни анализи. Разгледани са три проекта изпълнени в различни общини разположени в различни географски райони на страната, с типичен за областта климат и разполагаем ВЕИ ресурс.

Направен е сравнителен анализ между резултатите от комплексния модел и такива получени от най-популярните и приложими в момента компютърни модели и софтуери.

Автори: С. Петкова, Н. Тодоров – “EИ ЕН БИ СИ” ООД

A complex computing model for prediction and evaluation of the RES potential

Abstract: The paper presents the data analysis and assessments of the practical implementation of an innovative comprehensive model for assessment of the renewable energy potential, comparative analysis between conventional and renewable technologies and an assessment of market potential and market penetration of renewable technologies and forecast analysis. Comparative analysis between the final model results and the most popular available on the market software.

Authors: S. Petkova, N. TodorovENBC Ltd.



Comparative analysis of existed software and computing models for assessment of the energy potential of renewable energy sources

Abstract: In the paper is presented comparative analysis of different models for assessment of energy potential of renewable energy sources (wind, solar, hydro, geothermal, biomass, biogas). The analysis is based on preliminary selected/identified criterion for assessment of the models as: scope of the model, structure of the model, sensitive of the model, functionality of the model, sphere of implementation of the model. In the paper are presented 8 models, following the good practice in the European countries, including 2 models developed in Bulgaria.

Authors: доц. A. GrigorovS. Petkova

The full article is available in Bulgarian.