using.observeAsState()时改变MutableLiveData的值后如何开始执行一段代码？

Question

How to start executing a block of code after changing the value of MutableLiveData when using.observeAsState()?

Example: MutableLiveData changes and after need to call Toast.

@Composable
fun TextInfo() {
    val isSuccess by remember { viewModel.isSuccess.observeAsState() }//var isSuccess = MutableLiveData<Boolean>() — in ViewModel

    LaunchedEffect(isSuccess) {
        Log.d("IS SUCCESS", "trues")
    }
}

Answer 1

Showing a Toast is a side effect, so you need to put it inside a LaunchedEffect. Make the LiveData state the key of the LaunchedEffect. This causes the side effect to only occur when this particular LiveData's value changes.

val myDataState = remember { someLiveData.observeAsState() }
LaunchedEffect(myDataState) {
    // show the toast
}

Read about it in the documentation here .