Android is one of the most popular operating systems for modern devices. Smartphones, tablets, e-books, game consoles, netbooks, televisions are working on its basis. There are also wearable devices — gadgets such as Android Wear-based watches, step trackers, fitness bracelets, and glasses. However, Android mobile app development is a complicated and time-consuming task. That is why companies choose first to construct patterns to ease their work.
Design patterns are adapted to solve the most common problems, the main purpose of which is to describe the interaction of objects in an application. A pattern is not a complete design and cannot be directly converted to code. This is just an auxiliary framework for the task, which can significantly simplify the creation of an app.
Most developers today use an object-oriented approach to programming when working on large projects, or at least are familiar with its basic concept. It is difficult, and sometimes even impossible, to begin serious work from scratch, without using patterns in the code, or at least in the design. In this regard, programmers need to highlight key points for themselves from each project. Abstracting from any specific tasks, they build a mobile app framework for future developments.
Let’s consider the three most widely used patterns for android application creation: MVC, MVP, and MVVM.
The Model-View-Controller design pattern formed the basis for the architectural solution of the first programming environment with a graphical user interface — Smalltalk-80. MVC was first described back in 1978 by Trygve Reenskaug, who worked for some time in the Xerox PARC laboratory.
The architecture of the Model-View-Controller allows you to separate the data model, user interface, and control logic into three separate components. Moreover, a change in one component does not affect the work of the rest. Using this architecture is especially convenient for teamwork on large mobile app development projects. For example, when developing an application, you can separate the development of the part of the site that is responsible for data processing, absolutely not worrying about how this data will be presented. Why? Because layouts and designs for the application interface can be absolutely independently created
As for programmers, they can also share their work. For example, some developers can focus on developing the program logic, and another on designing the database structure. When using MVC, it becomes possible to distribute the work of the team, thereby increasing overall performance.
Model is generally understood as a component of data administration. In most cases, this refers to communication with databases: a selection of specific data, adding new ones, and changing existing ones. The model does not know in what form it is necessary to present the data requested from it to the user; it only performs operations with “raw” data. It should have a standardized universal interface so that one model can use any number of other subsystems any number of times.
View describes the format of data output to the user, that is, a visual representation of the data taken from the Model. It receives at the input a set of raw data that must be transmitted to the user and formats it following the requirements of the user.
Controller manages/handles all application processes. It handles external requests and fulfills the requirements contained in these requests. After that, it gives out relevant instructions to the Model. Then, it transfers the info received from the Model to the appropriate situation for the View. This is done to represent the necessary information correctly.
MVP is a design template derived from MVC that is used mainly to build a user interface. The template first appeared in IBM and then used in Taligent in the 1990s. The MVP, unlike the MVC, has a slightly different approach.
MVP scheme is similarly made up of three components. The Presenter is not required to adhere to the model changes. Now the Presenter (bearer), gives the idea of changes. This approach allows you to create a presentation abstraction. You can implement this template by rendering view interfaces. Each presentation will have interfaces with specific sets of methods and properties required bearer. Bearer, in turn, initialized with this interface, subscribes to the event of the performance and, if necessary, data is suppressed.
MVVM is a template that has emerged to circumvent the limitations of MVC and MVP patterns and brings together some of their strengths. It is used when designing an application architecture. It was originally introduced to the community by John Gossman in 2005 as a modification of the MVP template. MVVM is focused on modern development platforms and has three main components:
Model: just like in the classic MVC, the Model represents the basic data needed to run the application (classes, structures).
View: a graphical interface, that is, a window, buttons, etc.
ViewModel is on one side an abstraction of the View and, on the other, provides a wrapper of the Model data to be linked. That is, it comprises a Model that is converted to a View, and it also contains commands that the View can use to influence the Model.
The Model-View-Controller is a classic pattern that has been successfully implemented in web development. MVP/MVVM is said to be better than MVC architecture. But first, there is a small number of sources explaining the MVP and MVVM architecture on the mobile app development. Second, there is no empirical evidence and careful analysis to support this view. Thus, developers still doubt whether it is worth moving from MVC to new architectures. Because such decisions require the refactoring of the whole scheme, which demands a lot of effort from creation to testing. Also, for those who have used MVP, reducing MVVM encoding may be appealing. However, this will also cause new problems.
So, the choice of a specific pattern is up to the developer, who determines a more suitable template for each particular case.