当我从挂起方法调用中获得结果时,我正在尝试更新挂起方法调用之间的 UI。例如,这是我的 ViewModel 类。方法 a((、b(( 和 c(( 是挂起方法。
class MainViewModel : ViewModel() {
lateinit var userLiveData: LiveData<String>
var repo = MainRepo()
fun startTest() {
userLiveData = liveData {
var a = repo.a()
System.out.println("@@@@@@@@ $a")
emit(a)
var b = repo.b(a)
System.out.println("@@@@@@@@ $b")
emit(b)
var c = repo.c(b)
System.out.println("@@@@@@@@ $c")
emit(c)
}
}
}
这是我的活动课,我正在观察实时数据
viewModel = ViewModelProviders.of(this).get(MainViewModel::class.java)
viewModel.startTest()
viewModel.userLiveData.observe(this, Observer {
text.text = it
})
和回购类
class MainRepo {
suspend fun a(): String{
delay(1000)
return "A"
}
suspend fun b(a: String): String{
delay(5000)
return a + "B"
}
suspend fun c(b: String): String{
return b + "-C"
}
}
我的问题是,如何在调用repo.a()
或repo.b()
或repo.c()
后使用结果更新UI。提前谢谢。
您可以使用具有协程的可变实时数据来实现此目的。此外,挂起函数只能由协程或另一个挂起函数调用。我已经测试了下面的代码。希望这有帮助。
您的视图模型:
val userLiveData = MutableLiveData<Map<String, String>>()
fun startTest() {
viewModelScope.launch {
var newVal = itemRepository.a()
userLiveData.value = mapOf("responseTime" to newVal)
newVal = itemRepository.b(newVal)
userLiveData.value = mapOf("downloadSpeed" to newVal)
newVal = itemRepository.c(newVal)
userLiveData.value = mapOf("uploadSpeed" to newVal)
}
}
活动:
itemViewModel.userLiveData.observe(viewLifecycleOwner, Observer { result ->
result.get("responseTime")?.let {
println("setting textField Response as :" +result["responseTime"])
}
result.get("downloadSpeed")?.let {
println("setting textField2 Download Speed is :" +result["downloadSpeed"])
}
result.get("uploadSpeed")?.let {
println("setting textField3 Upload Speed is :" +result["uploadSpeed"])
}
})
itemViewModel.startTest()
回购:
class MainRepo {
suspend fun a(): String{
delay(1000)
return "A"
}
suspend fun b(a: String): String{
delay(5000)
return a + "B"
}
suspend fun c(b: String): String{
return b + "-C"
}
}
输出:
setting textField Response as :A
setting textField2 Download Speed is :AB
setting textField3 Upload Speed is :AB-C