Now-days almost every Android app uses a REST web API for data transfer. This makes me think what are the best practices to parse data and images from a REST web service. Earlier I used to prefer, writing my own code for parsing data. But now we have a whole range of REST client libraries, which can speed up the development, by reducing coding efforts and parsing data efficiently. Android Volley and Retrofit are two of the most used libraries for accessing REST web APIs today. For any one choosing between them is a difficult task. In this article we will not only compare Android Volley vs Retrofit, but will also discuss, out of these two, taking which one would be a better approach.

Research has proven that using an external library like Android Volley or Retrofit, definitely reduces time taken to parse a response. Therefore if you are building up a new project, I would strongly recommend to use either one of them to enhance your development. These libraries not only ease the development effort but also, give you many great features like retry mechanism, automatic parsing of data and caching. Although these libraries can increase the size of your apk a little, but still they are worth it. Before starting the comparison let me first introduce these libraries:

Volley Library:

Volley is a networking library, developed by Google engineers. It was introduced in Google IO 2013, it offers great features like synchronous requests, asynchronous requests, prioritization, making multiple requests at the same time, ordered requests and of course caching. But one of the major problems faced by developers using this library is that it lacks detailed official documentation. Hence if you wish to learn more about it please refer to some of my tutorials:

1. Android Volley Tutorial
2. Synchronous Volley Request
3. Loading Images Through Volley

Retrofit Library v1.9.0:

On the other hand Retrofit is a clean, simple, and light library for Android by Square, Inc. In other words, Retrofit is a REST client for Android, through which you can make easy to use interfaces which can turn any Android app into a powerful one. What makes it different is that, Retrofit can perform Async and sync requests with automatic JSON parsing without any effort. This feature alone makes it powerful enough to make a contender for this comparison. Although it has many more easy to use features, please refer to one of my tutorials to read more about them:

1. Android Retrofit Example

Android Volley vs Retrofit

1) Request Execution

One of the most important factors effecting the code complexity is, how a request is executed in your code. In background or in foreground? As you may know that Android OS does not allow the network interaction on main thread, it throws a NetworkOnMainThreadException. To avoid this you may need to do all the network processing in background. As a matter of fact both Android Volley and Retrofit support the background requests. Also both of them are designed in a way, that you may not have to write huge amounts of code to perform such requests. Although if you wish to do a request in foreground, even that it possible in both. As there are situations when you may want to block user from going further ahead in your app until a response is captured from web API.

2) In-Built Request Types

The data returned from a web service always complicates the implementation, but thankfully now with help of these libraries almost all types of responses can be captured. Android Volley can capture four types of responses automatically through these requests:

1. StringRequest – Make this type of request and the returned data is parsed and converted in to a String.
2. JsonObjectRequest – This type of request converts the response in to a JSONObject.
3. JsonArrayRequest – Make this type of request and response is automatically converted into a JSONArray.
4. ImageRequest – This type of request converts the response into a decoded bitmap automatically.

On the other hand Retrofit can parse many other types of responses automatically like:

1. Boolean – Web API response needs to be a String boolean.
2. Integer – Web API response needs to be an integer.
3. Date– Web API response should be Long format date.
4. String – Web API response needs to be in String format.
5. Object – Web API response needs to be in Json object.
6. Collections – Web API response needs to be in a String Format.

Now when comparing Android Volley vs Retrofit, volley may have image parsing feature but it cannot convert a Json object directly into a POJO (Plain Old Java Object). On the other hand retrofit can automatically convert a JSON object into a POJO, but lacks image parsing.

3) Retry Mechanism

One of the great things about volley is that it supports retries on request timeout. While creating requests with volley, we can set a retry policy by using setRetryPolicy method. By default a volley request timeout time is set to 5 seconds. But if you wish to change the policy, it supports that too. You can specify these parameters according to your needs:

• Timeout
• Number Of Retries
• Back Off Multiplier

Retrofit on the other hand does not have a retry mechanism as of now. Although I just saw their road map for 2.0 version, they might have a retry mechanism then. Therefore as of now when comparing Android Volley vs Retrofit, Retrofit loses this one.

4) Caching

Android Volley library has a very elaborate caching mechanism. This is one of the best features of volley. When a request is made through volley first it is checked in the cache. If an appropriate response is present in cache then it is parsed and returned directly to main thread, else a network request is made. This whole functionality can be customized, to support your requirements. If you wish to learn more about it please go through this document.

Retrofit on the hand, does not support caching. Although it can implement RFC 2616 caching which is the spec for HTTP caching, through the OkHttpClient. As stated in this document. Therefore when comparing caching between Android Volley and Retrofit, Volley takes this one too.

5) Loading Images

Volley library has a special type of request to get images from network called ImageRequest. When this type of request is made, response is captured as a bitmap. Also it supports the resizing of returned image in the worker thread itself, which saves a lot of coding. Volley also has a NetworkImageView class which can be used with ImageLoader class, to automatically load images, whenever the NetworkImageView appears. Read this tutorial for more information about it.

As of now Retrofit does not support the loading of images, the way they are loaded in Volley. But it can be combined with OkHttpClient to support the loading of images. Hence volley takes this one too.

6) Code Complexity

Both the libraries Android Volley and Retrofit are very easy to implement. If you compare them with primitive ways of accessing a web API, both of them would come out as a winner as they can phenomenally reduce your code base. But in my opinion when you compare the Android Volley vs Retrofit, the later one- Retrofit wins this one. As there is not much to customize in Retrofit. Its a simple yet powerful library. Volley on the other hand is highly customizable and has a greater code complexity.

Conclusion

After thoroughly comparing the major features between Android Volley and Retrofit. In my personal opinion Volley is a better library. It may be a little complex but it offers much more features than Retrofit. Volley not only supports caching of requests but can also load images automatically. But one of the best things about Retrofit is that it supports automatic parsing of responses, to their respective data types. And its light too. Hope this Android Volley vs Retrofit comparison helped you. Connect with though Facebook, Google+, and Twitter for more updates.

Mohit Gupt

Born in New Delhi, India. A software engineer by profession, an android enthusiast and mobile development evangelist. My motive here is to create a group of skilled engineers, who can build better software. Reason being programming is my passion, and also it feels good to make a device do something you want. Professionally I have worked with many software engineering and product development firms. As of now too, I am employed as a senior engineer in a leading tech company. In total I may have worked on more than 20 projects professionally, but whenever I get spare time I share my thoughts here at Truiton.

www.truiton.com

The post Android Volley vs Retrofit | Better Approach? appeared first on Truiton.

Recently a new framework was introduced for Android in Google I/O called Android Volley. This new framework was introduced to reduce the complexity involved in fetching data over network. Being Android developers we all know that fetching data over network is one of the most common task that one has to perform in any Android app. Therefore this new Android Volley library could be a game changer in Android app development. This library pitches in a lot of new features, but the question here is, do we need all these features? Here in this sum up, we would discuss the features of Android Volley vs AsyncTask.

Whenever some new component or library is released, being a developer, first thoughts that come into my mind are:

1. Why should I use it in my current code base?
2. Would it ease my development?
3. Would it improve my app’s functionally?

In short, the answer to all these questions would be: Maybe. As its not always possible to adapt to something new in your current code base. Unless you are planning to refactor the code completely. Although if you see things from a different perspective, new is always better. Since android volley is just a framework on top of existing android framework. This framework is utilizing the power of android in best possible way. Therefore it may turn out to be very helpful for developers.

Android Volley vs AsyncTask

To start of we will discuss both the approaches individually. First lets begin with AsyncTask as its the older one.

AsyncTask

Usually in android, simply when one need to access a web API, an AsyncTask is used. Its the standard way to do it in android. You may have also observed that AsyncTask is used in many official code samples. Like whenever a new login activity is inserted through the ADT in eclipse, it gives you a stub AsyncTask where you are supposed to write the code for accessing the login API.

The basic code structure used to access data through the AsyncTask is:

public class MyAsyncTask extends AsyncTask<Void, Void, Void> {
    @Override
    protected void onPreExecute() {
        //UI Interaction
    }

    @Override
    protected Void doInBackground(Void... params) {
        //Background Task
        return null;
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        //UI Interaction
    }
}

Main methods used to access the data from network by AsyncTask are:

1. onPreExecute() – Usually used to start the loading bar, as this method can interact with UI thread.
2. doInBackground(Void... params) – Main method in AsyncTask implementation where all the network access code is written. This method has a limitation that it cannot interact with UI thread.
3. onPostExecute(Void aVoid) – This is the method where result from doInBackground is passed as an argument. Since this method can interact with UI thread. It is used to update the screen with results.

A point to note here is that, in the implementation of doInBackground, one would have to write code to access network, and use classes like HttpURLConnection etc. Although if you are trying to access a completely custom implementation of web APIs this may serve your purpose better. Using AsyncTask to fetch data from network is not a bad approach at all, its just that you don’t get out of the box features like volley has.

Android Volley

Moving forward with this Android Volley vs AsyncTask sum up, let’s have an overview of Android volley.

As mentioned volley is a framework on top of android framework. It simply utilizes the power of android to access the network in best possible way. One of the many advantages of volley is that, you don’t need to write code for accessing network. All of this is managed by volley itself. Whenever a new network request is created, a background thread is spawned for network processing. Whose life-cycle is maintained by volley itself. In default implementation of volley, at a time 4 network threads can do processing simultaneously. To learn in detail about volley, please have a look at this Android Volley example.

With Volley you also get many more out of the box features like:

1. Retry Mechanism
2. Caching
3. Multiple Request Types
   1. JsonObjectRequest
   2. JsonArrayRequest
   3. StringRequest
   4. ImageRequest

Difference between Android Volley and AsyncTask

Like I have been saying new is always better. Using AsyncTask has been a good approach, but consider Android Volley as a 2.0 version of it. It has many improvements over AsyncTask, as volley is designed for the purpose of network access. A major advantage of Android Volley over AsyncTask is that you can do multiple requests simultaneously without the overhead of thread management. Also I believe retry mechanism is a great feature of volley which gives it an edge over AsynTask. Another advantage of volley over AsyncTask is that it provides you with multiple request types, through which complex requests can be made easily. On the other hand while using AsyncTasks one would have to create this type of request manually.

Although best approach differs from application to application. Like if you have less no of requests to make, you can use AsyncTask. As for volley, one has to import a library project which increases your project size. Hence pick wisely between volley and AsyncTask. Hope this Android Volley vs AsyncTask sum up helped you choose. Please like our Facebook and Google+ page for more updates.

Mohit Gupt

Born in New Delhi, India. A software engineer by profession, an android enthusiast and mobile development evangelist. My motive here is to create a group of skilled engineers, who can build better software. Reason being programming is my passion, and also it feels good to make a device do something you want. Professionally I have worked with many software engineering and product development firms. As of now too, I am employed as a senior engineer in a leading tech company. In total I may have worked on more than 20 projects professionally, but whenever I get spare time I share my thoughts here at Truiton.

www.truiton.com

The post Android Volley vs AsyncTask | Better Approach? appeared first on Truiton.