无法在 Jetpack Compose 中显示来自 onClick 的 AlertDialog

Question

我一直试图在Card onClick AlertDialog的 AlertDialog。

我收到编译时错误@Composable 调用只能在@Composable function 的上下文中发生。

下面是我的代码片段：

@Preview(showBackground = true)
@Composable
fun prepareCard(card: Card) {
    MyApplicationTheme() {
        androidx.compose.material.Card() {
            Column(Modifier.clickable {
                Log.d("TAG", "clicked : " + card.name)
                val showDialog = mutableStateOf(true)

                if (showDialog.value) {
                    alert(card)
                }
                 ...
            }
        }
     }

我已经从上面的代码中调用了alert()可组合 function

@Composable
fun alert(card : Card) {
    AlertDialog(
        title = {
            Text("")
        },
        text = {
            Text(text = card.name)
        }, onDismissRequest = {
        },
        confirmButton = {},
        dismissButton = {}
    )
}

如图所示，我收到编译时错误

请帮助解决这个问题

笔记：

我已经尝试过如下修改，它解决了编译时错误，但点击Card时仍然没有显示AlertDialog

@Preview(showBackground = true)
@Composable
fun prepareCard(card: Card) {
    MyApplicationTheme() {
        val showDialog = mutableStateOf(false)


        if (showDialog.value) {
            alert(card)
        }

        androidx.compose.material.Card() {
            Column(Modifier.clickable {
                Log.d("kushal", "clicked : " + card.name)
                showDialog.value = true
            }) {
            ...
           }
         }

Answer 1

使用showDialog中的remember来解决不显示AlertDialog的问题。

val showDialog = remember { mutableStateOf(false) }
if (showDialog.value) {
     // alert...
}
Card() {
   Column(Modifier.clickable(
     onClick = {showDialog.value = true})
   ) {}
}

同样在您的Alert() function 中，您应该处理 state。

@Composable
fun Alert(name: String,
          showDialog: Boolean,
          onDismiss: () -> Unit) {
    if (showDialog) {
        AlertDialog(
            title = {
                Text("Title")
            },
            text = {
                Text(text = name)
            }, 
            onDismissRequest = onDismiss,
            confirmButton = {
                TextButton(onClick = onDismiss ) {
                    Text("OK")
                }
            },
            dismissButton = {}
        )
    }
}

并调用它：

val showDialog = remember { mutableStateOf(false) }

Card() {
    if (showDialog.value) {
        Alert(name = "Name",
            showDialog = showDialog.value,
            onDismiss = {showDialog.value = false})
    }
    Column(Modifier.clickable(
        onClick = {showDialog.value = true})
    ) {}
}

Answer 2

您可以像下面的代码一样更新您的代码 ->

@Composable
fun alert() {
MaterialTheme {
    Column {
    val openDialog = remember { mutableStateOf(false)  }

        Button(onClick = {
            openDialog.value = true
        }) {
            Text("Click me")
        }

        if (openDialog.value) {

            AlertDialog(
                onDismissRequest = {
                    // Dismiss the dialog when the user clicks outside the dialog or on the back
                    // button. If you want to disable that functionality, simply use an empty
                    // onCloseRequest.
                    openDialog.value = false
                },
                title = {
                    Text(text = "Dialog Title")
                },
                text = {
                    Text("Here is a text ")
                },
                confirmButton = {
                    Button(

                        onClick = {
                            openDialog.value = false
                        }) {
                        Text("This is the Confirm Button")
                    }
                },
                dismissButton = {
                    Button(

                        onClick = {
                            openDialog.value = false
                        }) {
                        Text("This is the dismiss Button")
                    }
                }
            )
        }
    }

}
}

Answer 3

这是使用状态显示对话框的推荐方式。

val openDialog = remember { mutableStateOf(true) }
val dialogWidth = 200.dp
val dialogHeight = 50.dp

if (openDialog.value) {
    Dialog(onDismissRequest = { openDialog.value = false }) {
        // Draw a rectangle shape with rounded corners inside the dialog
        Box(Modifier.size(dialogWidth, dialogHeight).background(Color.White))
    }
}