MVVM pattern definition

📌 MVVM stands for Model, View, ViewModel.

View

• It represents the UI of the application devoid of any Application Logic.
• It observes the ViewModel.

ViewModel

• It acts as a link between the Model and the View.
• It’s responsible for transforming the data from the Model.
• It provides data streams to the View.
• It also uses hooks or callbacks to update the View.
• It’ll ask for the data from the Model.

Model

• This holds the data of the application.
• It cannot directly talk to the View.
• It’s recommended to expose the data to the ViewModel through Observables

Android implementation components

📢 The following components are required to implement the sample app with Android and Kotlin. We will have two implementations: Simple MVVM with a text view and Simple MVVM with Recycle View.

View Binding

• View binding is a feature that allows you to more easily write code that interacts with views. Once view binding is enabled in a module, it generates a binding class for each XML layout file present in that module.
• An instance of a binding class contains direct references to all views that have an ID in the corresponding layout.

📌 In most cases, view binding replaces findViewById.

View Binding | Android Developers

View binding is a feature that allows you to more easily write code that
interacts with views. Once view binding is enabled in a module, it generates a
binding class for each XML layout file present in that module. An instance of
a binding class contains direct references to all views that have an I…

ViewModel

• The ViewModelclass is designed to store and manage UI-related data in a lifecycle conscious way.
• The ViewModelclass allows data to survive configuration changes such as screen rotations.

ViewModel overview | Android Developers

ViewModel lets you manage your UI's data in a lifecycle-aware fashion.

Lifecycle

• Lifecycle-aware components perform actions in response to a change in the lifecycle status of another component, such as activities and fragments. These components help you produce better-organized, and often lighter-weight code, that is easier to maintain.

Lifecycle | Android Developers

Lifecycle-aware components perform
actions in response to a change in the lifecycle status of another component,
such as activities and fragments. These components help you produce
better-organized, and often lighter-weight code, that is easier to maintain.

LiveData

• LiveDatais an observable data holder class.
• Unlike a regular observable, LiveData is lifecycle-aware, meaning it respects the lifecycle of other app components, such as activities, fragments, or services.
• This awareness ensures LiveData only updates app component observers that are in an active lifecycle state.

LiveData overview | Android Developers

Use LiveData to handle data in a lifecycle-aware fashion.

Recycler View

• RecyclerView makes it easy to efficiently display large sets of data.
• You supply the data and define how each item looks, and the RecyclerView library dynamically creates the elements when they’re needed.

Implementing your adapter and view holder

• Once you’ve determined your layout, you need to implement your Adapterand ViewHolder.
• These two classes work together to define how your data is displayed.
• The ViewHolderis a wrapper around a View that contains the layout for an individual item in the list.
• The Adaptercreates ViewHolderobjects as needed, and also sets the data for those views. The process of associating views to their data is called binding.

Create dynamic lists with RecyclerView | Android Developers

RecyclerView makes it easy to efficiently display large sets of data. You supply
the data and define how each item looks, and the RecyclerView library
dynamically creates the elements when they’re needed.

MaterialCardView

• This class supplies Material styles for the card in the constructor.
• The widget will display the correct default Material styles without the use of a style flag.

MaterialCardView | Android Developers

Github Repositories

TaskApp MVVM

GitHub – una-eif411-progra-mobile-master/frontend-taskapp-android at mvvm

Front End Android for TaskApp. Contribute to una-eif411-progra-mobile-master/frontend-taskapp-android development by creating an account on GitHub.

TaskApp MVVM RecycleView

GitHub – una-eif411-progra-mobile-master/frontend-taskapp-android at mvvm-recycleview

Front End Android for TaskApp. Contribute to una-eif411-progra-mobile-master/frontend-taskapp-android development by creating an account on GitHub.