Jetpack Compose Basics - Preview and it’s parameters

val sheetState = rememberModalBottomSheetState(
    initialValue = ModalBottomSheetValue.Hidden,
    confirmStateChange = { it != ModalBottomSheetValue.HalfExpanded }
)

   fun main() {
        si(true){
            println("True")
        } sino {
            println("False")
        }
        
        val result = si(true){
            println("True")
        } sino {
            println("False")
        }
        println(result)

    }
    private fun si(booleano: Boolean, function: () -> Unit):Boolean{
        if(booleano){ function()}
        return booleano
    }
    private infix fun Boolean.sino(function: () -> Unit) {
		if(!this){
            function()
        }
    }

go to the project's res folder and delete the duplicated folder 
in my case anydpi folder 

class viewModel() : ViewModel() {

   private val _sharedFlow = MutableSharedFlow<Int>() // Mutable Share Flow

   val sharedFlow = _sharedFlow.asSharedFlow()  // Immutable Share Flow

   fun squareNumber(number:Int){
       viewModelScope.launch {
           _sharedFlow.emit(number * number)
       }
   }


   init {
       viewModelScope.launch {
           sharedFlow.collect {
               delay(2000L)
               println("First Flow : The received Number is $it")
           }
       }
       viewModelScope.launch {
           sharedFlow.collect {
               delay(3000L)
               println("Secound Flow : The received Number is $it")
           }
       }

       squareNumber(3)
   }
}

class MainActivity : AppCompatActivity() {

   lateinit var button: Button
   lateinit var counter: TextView
   val view_model:ViewModel = viewModel()

   override fun onCreate(savedInstanceState: Bundle?) {
       super.onCreate(savedInstanceState)
       setContentView(R.layout.activity_main)

       button = findViewById(R.id.button)

       counter = findViewById(R.id.counter)

       lifecycleScope.launch {
           repeatOnLifecycle(Lifecycle.State.STARTED) {
               (view_model as viewModel).stateFlow.collectLatest { number ->
                  counter.text = number.toString()
               }
           }
       }

       button.setOnClickListener{
           (view_model as viewModel).incrementCounter()
       }

   }

}

class viewModel() : ViewModel() {

   private val _stateFlow = MutableStateFlow(0);  // Mutable State Flow

   val stateFlow = _stateFlow.asStateFlow();  // Immutable State Flow

   fun incrementCounter(){  // changes the state
       _stateFlow.value +=1;
   }
  
}

/**
 * Used as a wrapper for data that is exposed via a LiveData that represents an event.
 */
open class Event<out T>(private val content: T) {

    var hasBeenHandled = false
        private set // Allow external read but not write

    /**
     * Returns the content and prevents its use again.
     */
    fun getContentIfNotHandled(): T? {
        return if (hasBeenHandled) {
            null
        } else {
            hasBeenHandled = true
            content
        }
    }

    /**
     * Returns the content, even if it's already been handled. */ fun peekContent(): T = content }Copy the code

@Preview(device = Devices.PIXEL_3A)
@Composable
fun ExamplePreview() {...}

@Preview(uiMode = UI_MODE_NIGHT_NO)
@Preview(uiMode = UI_MODE_NIGHT_YES)
@Composable
fun ExamplePreview() {...}

@Preview(showBackground = true, backgroundColor = 0xff0000)
@Composable
fun ExamplePreview() {...}

@Preview
@Preview(locale = "fr")
@Composable
fun ButtonPreview() {
  Button(
    ...
    content = { Text(text = stringResource(id = R.string.day_monday)) })
}

@Preview(widthDp = 100, heightDp = 100)
@Composable
fun ExamplePreview() {...}

@Preview(group = "Buttons")
@Composable
fun ButtonEnabledPreview() {...}

@Preview(group = "Buttons")
@Composable
fun ButtonDisabledPreview() {...}

@Preview(group = "Texts")
@Composable
fun TextBigPreview() {...}

@Preview(group = "Texts")
@Composable
fun TextSmallPreview() {...}

@Preview(name = "Some preview name")
@Composable
fun ExamplePreview() {
  ...
}

val name: String = "",
val group: String = "",
@IntRange(from = 1) val apiLevel: Int = -1,
val widthDp: Int = -1,
val heightDp: Int = -1,
val locale: String = "",
@FloatRange(from = 0.01) val fontScale: Float = 1f,
val showSystemUi: Boolean = false,
val showBackground: Boolean = false,
val backgroundColor: Long = 0,
@UiMode val uiMode: Int = 0,
@Device val device: String = Devices.DEFAULT