Android应用程序演示了Kotlin Coroutines StateFlow的使用

Android应用程序演示了Kotlin Coroutines StateFlow的使用

StateFlow - Demo

What is StateFlow?

It is a flow which emits updates to its collectors.Value can be observed by collecting values from the flow.

Implementation

ViewModel.kt:

class MainViewModel : ViewModel() { private val _countState = MutableStateFlow(0) val countState: StateFlow = _countState fun incrementCount() { _countState.value++ } fun decrementCount() { _countState.value-- }}

MainActivity.kt:

class MainActivity : AppCompatActivity() { private val viewModel by lazy { ViewModelProvider(this)[MainViewModel::class.java] } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) initCountObserver() initView() } private fun initCountObserver() { lifecycleScope.launch { viewModel.countState.collect { value -> textview_count.text = "$value" } } } private fun initView() { button_plus.setOnClickListener(::incrementCounter) button_minus.setOnClickListener(::decrementCounter) } private fun incrementCounter(view: View) { viewModel.incrementCount() } private fun decrementCounter(view: View) { viewModel.decrementCount() }}

Reference

StateFlow

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