Can you explain the main principles and components of the MVVM architectural pattern?

MVVM (Model-View-ViewModel) — an architectural pattern that divides application logic into three components:

• Model — responsible for data and business logic. These can be objects working with network, database, etc.
• View — displays data to the user and handles user input. In Android, this is usually an Activity or Fragment.
• ViewModel — an intermediary between Model and View. It receives data from the Model, transforms it into a display-friendly format, and provides it to the View. It also handles user actions, passing them to the Model.

Main principles:

• Separation of UI from business logic for better testability and maintainability.
• ViewModel does not contain references to the View, allowing easy UI changes.
• Use of observable data (LiveData, Flow) to update the View when data changes.

Example in Kotlin with LiveData:

class MyViewModel : ViewModel() {
    private val _data = MutableLiveData<String>()
    val data: LiveData<String> = _data

    fun loadData() {
        // Get data from Model
        _data.value = "Hello, MVVM!"
    }
}

// In Activity
viewModel.data.observe(this) { value ->
    textView.text = value
}