Android Koin在片段及其宿主活动之间的SharedViewModel

我想通过使用ViewModel（如下：）在共享LiveData更改时更新活动的UI，实现片段与其宿主活动之间的通信

从模块中的declare ViewModel开始

main模块.kt

object MainModule {
    val module = module {
        viewModel {
            MainViewModel()
        }
    }
}

private val mainViewModel by viewModel<MainViewModel>()

private val mainViewModel by sharedViewModel<MainViewModel>()

mainViewModel.drawerState.observe(this, {
    // do something when it changed
})

mainButton.setOnClickListener {
    mainViewModel.toggleDrawerState()
}

private val _drawerState = MutableLiveData<DrawerState>()
val drawerState: LiveData<DrawerState> = _drawerState

fun toggleDrawerState() {
    if (_drawerState.value == DrawerState.OPENED) {
        _drawerState.value = DrawerState.CLOSED
    } else {
        _drawerState.value = DrawerState.OPENED
    }
}

enum class DrawerState {
    CLOSED, OPENED
}

然后将其注入活动和片段

MainActivity.kt

object MainModule {
    val module = module {
        viewModel {
            MainViewModel()
        }
    }
}

private val mainViewModel by viewModel<MainViewModel>()

private val mainViewModel by sharedViewModel<MainViewModel>()

mainViewModel.drawerState.observe(this, {
    // do something when it changed
})

mainButton.setOnClickListener {
    mainViewModel.toggleDrawerState()
}

private val _drawerState = MutableLiveData<DrawerState>()
val drawerState: LiveData<DrawerState> = _drawerState

fun toggleDrawerState() {
    if (_drawerState.value == DrawerState.OPENED) {
        _drawerState.value = DrawerState.CLOSED
    } else {
        _drawerState.value = DrawerState.OPENED
    }
}

enum class DrawerState {
    CLOSED, OPENED
}

单击按钮（在片段上）时更新LiveData

MainFragment.kt

object MainModule {
    val module = module {
        viewModel {
            MainViewModel()
        }
    }
}

private val mainViewModel by viewModel<MainViewModel>()

private val mainViewModel by sharedViewModel<MainViewModel>()

mainViewModel.drawerState.observe(this, {
    // do something when it changed
})

mainButton.setOnClickListener {
    mainViewModel.toggleDrawerState()
}

private val _drawerState = MutableLiveData<DrawerState>()
val drawerState: LiveData<DrawerState> = _drawerState

fun toggleDrawerState() {
    if (_drawerState.value == DrawerState.OPENED) {
        _drawerState.value = DrawerState.CLOSED
    } else {
        _drawerState.value = DrawerState.OPENED
    }
}

enum class DrawerState {
    CLOSED, OPENED
}

LiveData在ViewModel中声明

MainViewModel.kt

object MainModule {
    val module = module {
        viewModel {
            MainViewModel()
        }
    }
}

private val mainViewModel by viewModel<MainViewModel>()

private val mainViewModel by sharedViewModel<MainViewModel>()

mainViewModel.drawerState.observe(this, {
    // do something when it changed
})

mainButton.setOnClickListener {
    mainViewModel.toggleDrawerState()
}

private val _drawerState = MutableLiveData<DrawerState>()
val drawerState: LiveData<DrawerState> = _drawerState

fun toggleDrawerState() {
    if (_drawerState.value == DrawerState.OPENED) {
        _drawerState.value = DrawerState.CLOSED
    } else {
        _drawerState.value = DrawerState.OPENED
    }
}

enum class DrawerState {
    CLOSED, OPENED
}

---

但它不能按预期工作，这意味着单击按钮时不会发生任何事情（可以通过使用断点进行调试来保证）。我想知道我哪里做错了或误解了。谢谢。

当您在toggleDrawerState（）上执行postValue（DrawerState.CLOSED）时是否也一样？哇，现在可以了。你能再给我解释一下吗？为什么它应该使用“postValue（）”而不是“=”？我不确定，因为我不知道您的整个场景。也许，您的toggleDrawersState（）在主线程之外做了一些事情。为了避免这种问题，我倾向于在处理LiveData时使用postValue。