android - 尝试在将一个 Activity 更改为第二个 Activity 后保存编辑文本字段的值，然后返回到 jetpack compose 中的第一个 Activity

Question

1. 我尝试在从一项 Activity 更改为另一项 Activity 后保存编辑文本值
2. 例如:就像在注册寻呼机中一样(首先您必须填写页面中的所有数据，最后提交。
3. 我遇到的问题是，如果我想编辑第一页数据，所以我从第二页移到第一页，但我的第一页不显示任何数据
4. 我尝试使用保存状态和恢复导航状态，但没有帮助

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent { ScreenNavigation() }
    }
}

@Composable
fun Page1(navController: NavHostController) {
    var test = remember { mutableStateOf("") }

    Column() {
        TextField(value = test.value, onValueChange = { test.value = it })
        Button(
            onClick = {
                navController.navigate(ScreenRoute.Page2.name) {
                    popUpTo(ScreenRoute.Page2.name) { saveState = true }
                    launchSingleTop = true

                    restoreState = true
                }
            }
        ) {}

        Text(text = "Page1")
        TextField(
            value = test.value,
            onValueChange = { test.value = it },
        )
    }
}

@Composable
fun Page2(navController: NavHostController) {
    var test = remember { mutableStateOf("") }

    Column() {
        TextField(value = test.value, onValueChange = { test.value = it })
        Button(
            onClick = {
                navController.navigate(ScreenRoute.Page1.name) {
                    popUpTo(ScreenRoute.Page1.name) { saveState = true }
                    launchSingleTop = true

                    restoreState = true
                }
            }
        ) {}
        Text(text = "Page2")
    }
}

// code for navigation

@Composable
fun ScreenNavigation() {
    val navController = rememberNavController()

    NavHost(navController = navController, startDestination = ScreenRoute.Page1.name) {
        composable(ScreenRoute.Page1.name) { Page1(navController) }

        composable(ScreenRoute.Page2.name) { Page2(navController) }
    }
}

// code for screen route
enum class ScreenRoute {
    Page1,
    Page2,
}

Answer 1

在函数和上面的类之外都有变量，如下所示:

var test1 = mutableStateOf("")
var test2 = mutableStateOf("") 

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent { ScreenNavigation() }
    }
}

@Composable
fun Page1(navController: NavHostController) {
    

    Column() {
        TextField(value = test1.value, onValueChange = { test1.value = it })
        Button(
            onClick = {
                navController.navigate(ScreenRoute.Page2.name) {
                    popUpTo(ScreenRoute.Page2.name) { saveState = true }
                    launchSingleTop = true

                    restoreState = true
                }
            }
        ) {}

        Text(text = "Page1")
        TextField(
            value = test1.value,
            onValueChange = { test1.value = it },
        )
    }
}

@Composable
fun Page2(navController: NavHostController) {


    Column() {
        TextField(value = test2.value, onValueChange = { test2.value = it })
        Button(
            onClick = {
                navController.navigate(ScreenRoute.Page1.name) {
                    popUpTo(ScreenRoute.Page1.name) { saveState = true }
                    launchSingleTop = true

                    restoreState = true
                }
            }
        ) {}
        Text(text = "Page2")
    }
}

// code for navigation

@Composable
fun ScreenNavigation() {
    val navController = rememberNavController()

    NavHost(navController = navController, startDestination =       ScreenRoute.Page1.name) {
        composable(ScreenRoute.Page1.name) { Page1(navController) }

        composable(ScreenRoute.Page2.name) { Page2(navController) }
    }
}

// code for screen route
enum class ScreenRoute {
    Page1,
    Page2,
}