Google first introduced Volley Library, an HTTP Library during the Google I/O 2013. The primary motive of the library is to help in transmitting data over the network. With Volley, the networking can be made easier and faster for app development. One can find Volley via through AOSP(Android Open Source Project) repository.
Volley is a feature rich program that can automatically schedule wor requests, facilitate multiple concurrent connections, send a request for prioritization, initiate cancellation or blocking of a request, assist in easy UI management with the data fetched from the network asynchronously and also enables easier customization.
How Volley improves performance in Android:
To improve the performance of the apps, Volley uses cache concept. For instance, an app uses Asynctask to fetch an image and description stored in a JSON array that is created in server API. Once fetched, it is stored in a portrait mode, but, the user wants to tilt its phone and view it in a landscape mode. The entire activity thus gets destroyed and the app would fetch the data all over again. As it is all the way the same exercise, it is like wasting resources as well as offering poor user experiences.
With caches data, Volley offers you a solution to such a problem. Volley does not contact the server every time a user requests some data but shows it from the cache files and thus saves the resources as well as enhances the user experience.
What is RequestQueue and work process of Volley in Android?
RequestQueue is the managing agent that allows functionality to Volley, which is a library that is used to fetch data in small networks of Android System. If you want to use Volley, you need to find RequestQueue first and then you can start, stop, request or cancel any request to access caches.
RequestQueue queue = Volley.newRequestQueue(this);
Once instantiated RequestQueue you have to create a request now. To ease it down, Volley already has a few request classes enrolled in the website- String request, JSON request, an image request. However, you can anytime create a custom request.
JsonObjectRequest request = JsonObjectRequest(Request.Method.GET, URL, new ResponseListener(), new ErrorListener();
Four parameters of request construction:
To construct a request in Volley, there are 4 parameters to follow:
First Parameter: Request.Method.GET
This parameter is used to read. In case you need to pursue some other function, you can also use POST (for creating), PUT (for replacing or adding), Delete ( for deleting), Patch (for modifying or updates) and many such other.
Second Parameter: URL
This is the parameter that responds to the HTTP request.
Third Parameter: Successful Response Listener
Once the request is successfully submitted, this is where all the data goes to.