LiveData - TechStudy

Introduction to LiveData

LiveData Android Architecture Components का एक observable data holder class है। यह lifecycle-aware होता है और UI components को automatically update करता है जब data change होता है।

LiveData is an observable data holder class in Android Architecture Components. It is lifecycle-aware and automatically updates UI components when data changes.

Key Features (मुख्य विशेषताएं):

LiveData lifecycle-aware होता है
LiveData is lifecycle-aware
LiveData UI को automatically update करता है
LiveData automatically updates UI
LiveData memory leaks को prevent करता है
LiveData prevents memory leaks
LiveData configuration changes को handle करता है
LiveData handles configuration changes

Types of LiveData (लाइवडेटा के प्रकार)

LiveData के main types:

Main types of LiveData:

Type (प्रकार)	Description (विवरण)
MutableLiveData	Data को modify करने की permission देता है
MutableLiveData	Allows modification of data
MediatorLiveData	Multiple LiveData sources को observe करता है
MediatorLiveData	Observes multiple LiveData sources
Transformations	LiveData को transform करने के लिए utility methods provide करता है
Transformations	Provides utility methods for transforming LiveData

Implementation Example (इम्प्लीमेंटेशन उदाहरण)

LiveData को implement करने का example:

Example of implementing LiveData:

// ViewModel with LiveData
class UserViewModel : ViewModel() {
    private val _user = MutableLiveData()
    val user: LiveData = _user

    private val _loading = MutableLiveData()
    val loading: LiveData = _loading

    fun loadUser(userId: String) {
        _loading.value = true
        viewModelScope.launch {
            try {
                _user.value = repository.getUser(userId)
            } finally {
                _loading.value = false
            }
        }
    }
}

// Activity/Fragment implementation
class UserActivity : AppCompatActivity() {
    private lateinit var viewModel: UserViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        viewModel = ViewModelProvider(this).get(UserViewModel::class.java)
        
        viewModel.user.observe(this) { user ->
            // Update UI with user data
        }
        
        viewModel.loading.observe(this) { isLoading ->
            // Show/hide loading indicator
        }
        
        viewModel.loadUser("123")
    }
}

LiveData Transformations (लाइवडेटा ट्रांसफॉर्मेशन्स)

LiveData transformations के examples:

Examples of LiveData transformations:

// Map transformation
val userName: LiveData = Transformations.map(user) { user ->
    "${user.firstName} ${user.lastName}"
}

// SwitchMap transformation
val userPosts: LiveData> = Transformations.switchMap(user) { user ->
    repository.getPosts(user.id)
}

// MediatorLiveData example
val combinedData = MediatorLiveData().apply {
    addSource(user) { user ->
        value = CombinedData(user, posts.value)
    }
    addSource(posts) { posts ->
        value = CombinedData(user.value, posts)
    }
}

Best Practices (सर्वोत्तम प्रथाएं)

LiveData के साथ काम करने के best practices:

Best practices for working with LiveData:

Data Exposure: MutableLiveData को private रखें और public LiveData expose करें

Data Exposure: Keep MutableLiveData private and expose public LiveData

Transformations: Complex data transformations के लिए Transformations का use करें

Transformations: Use Transformations for complex data transformations

Error Handling: Error states को LiveData के through handle करें

Error Handling: Handle error states through LiveData

Testing: LiveData को easily testable बनाएं

Testing: Make LiveData easily testable