Value Is On Up Gradation!

With the passing of days, electronic gadgets are becoming more compact in the area of work as well as for the leisure activities and definitely the gadgets are coming with multi-functionalities, which were not introduced before. Naturally, the craze for electronic gadgets has raised a mere competition among the companies who are working in the common sector. While talking about electronic gadget the best example can be given of computers and mobile phones (which are presently dominating the market). Nowadays, most of the capabilities of an electronic computer are being driven to the mobile phones, which in turn are increasing the mobile market demand. Especially, when it comes to customer satisfaction, none other than Android, which is ruling the present market! The positives and the versatile capabilities have made Android the largest selling phone across the globe. Apart from this, the collection of applications that the phone possesses makes it unique in terms of reliability and usability. The most important aspect of Android is its compatibility with different phones, which makes its more friendly among users unlike iPhone that targets a sole device. The major reason behind the adaptability of iPhone is due to the extensibility factor.

The Android phone works like a PC that extends the different functionalities and keep itself updated with the help of Android application development companies. Emphatically, considering the present market, the increase in demand of the Android application development services resulted into the popularity of the Android phones. People are more inclined in getting a customized app than downloading an app from the app store directly. Thus, the dependency of the users is increasing with the time over the app development services provider firms. Where as, on the other hand, the apps that are available in the app store do not fulfill the requirements of the user completely as per their desire. So, it is a wiser option to go for the customized Android app development services than going for the ready made one in the app store. Android application development services are something that cannot be accomplished with the services offered by a rookie. Professionalism matters while dealing with mass needs. So, it is always a good option to hire the professional Android application development services provider firm than going for anyone else. Finally, the best can be chosen by you for your business! Openxcell is an Android application development company. And apart from that Internet marketing services, OpenXcell even deals with mobile application development services.

This is where the LiveData class comes in. LiveData is an observable data holder. It lets the components in your app observe LiveData objects for changes without creating explicit and rigid dependency paths between them. LiveData also respects the lifecycle state of your app components (activities, fragments, services) and does the right thing to prevent object leaking so that your app does not consume more memory. Now we replace the User field in the UserProfileViewModel with a LiveData so that the fragment can be informed when the data is updated. The great thing about LiveData is that it is lifecycle aware and will automatically clean up references when they are no longer needed. Now we modify UserProfileFragment to observe the data and update the UI. Every time the user data is updated, the onChanged callback will be invoked and the UI will be refreshed. If you are familiar with other libraries where observable callbacks are used, you might have realized that we didn't have to override the fragment's onStop() method to stop observing the data.

The ViewModel is automatically restored when the configuration changes, so as soon as the new fragment comes to life, it will receive the same instance of ViewModel and the callback will be called instantly with the current data. This is the reason why ViewModels should not reference Views directly; they can outlive the View's lifecycle. See The lifecycle of a ViewModel. Now we have connected the ViewModel to the fragment, but how does the ViewModel fetch the user data, In this example, we assume that our backend provides a REST API. We will use the Retrofit library to access our backend though you are free to use a different library that serves the same purpose. A naive implementation of the ViewModel could directly call the Webservice to fetch the data and assign it back to the user object. Even though it works, your app will be difficult to maintain as it grows.

It gives too much responsibility to the ViewModel class which goes against the principle of separation of concerns that we've mentioned earlier. Additionally, the scope of a ViewModel is tied to an Activity or Fragment lifecycle, so losing all of the data when its lifecycle is finished is a bad user experience. Instead, our ViewModel will delegate this work to a new Repository module. Repository modules are responsible for handling data operations. They provide a clean API to the rest of the app. They know where to get the data from and what API calls to make when data is updated. You can consider them as mediators between different data sources (persistent model, web service, cache, etc.). The UserRepository class below uses the WebService to fetch the user data item. Even though the repository module looks unnecessary, it serves an important purpose; it abstracts the data sources from the rest of the app. Now our ViewModel does not know that the data is fetched by the Webservice, which means we can swap it for other implementations as necessary.