Jetpack Compose val cannot be reassigned

June 25, 2023

I want to pass state but it throws error "val cannot be reassigned".

@Composable
fun MyUi() {
    var showContent by remember { mutableStateOf(false) }
    if (showContent) {
        MyButton(showContent)  
    }
}

@Composable
fun MyButton(showContent: Boolean) {
    // very long content
    Button(onClick = {
        showContent = true
    }) {
        Text(text = "Very long content")
    }
}

>Solution :

You should make your composables statelesss and pass events up, change it like this, where the top composable is responsible for mutating the flag

@Composable
fun MyUi() {
    var showContent by remember { mutableStateOf(false) }
    if (showContent) {
        MyButton(
            onClick = {
                showContent = true
            }
        )
    }
}

@Composable
fun MyButton(onClick: () -> Unit) {
    // very long content
    Button(onClick = onClick) {
        Text(text = "Very long content")
    }
}