我正在开发新的android应用程序，但出现以下异常
java.lang.ClassCastException: kotlinx.coroutines.CompletableDeferredImpl cannot be cast to java.util.List
at yodgorbek.komilov.musobaqayangiliklari.viewmodel.MainViewModel$loadNews$1.invokeSuspend(MainViewModel.kt:42)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
at kotlinx.coroutines.DispatchedTask.run(Dispatched.kt:241)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:201)
at android.app.ActivityThread.main(ActivityThread.java:6820)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:922)
在我的MainViewModel.kt中
在我的MainViewModel.kt下面
@Suppress("UNCHECKED_CAST")
class MainViewModel(val newsRepository: NewsRepository) : ViewModel(), CoroutineScope {
// Coroutine's background job
val job = Job()
// Define default thread for Coroutine as Main and add job
override val coroutineContext: CoroutineContext = Dispatchers.Main + job
val showLoading = MutableLiveData<Boolean>()
val sportList = MutableLiveData <List<Article>>()
val showError = SingleLiveEvent<String>()
fun loadNews() {
// Show progressBar during the operation on the MAIN (default) thread
showLoading.value = true
// launch the Coroutine
launch {
// Switching from MAIN to IO thread for API operation
// Update our data list with the new one from API
val result = withContext(Dispatchers.IO) {
newsRepository?.getNewsList()
}
// Hide progressBar once the operation is done on the MAIN (default) thread
showLoading.value = false
when (result) {
is UseCaseResult.Success<*> -> {
sportList.value = result.data as List<Article>
}
is Error -> showError.value = result.message
}
}
}
override fun onCleared() {
super.onCleared()
// Clear our job when the linked activity is destroyed to avoid memory leaks
job.cancel()
}
}
低于Article.kt
@Entity(tableName = "news_table")
data class Article(@ColumnInfo(name = "author")val author: String,
val content: String,
val description: String,
val publishedAt: String,
val source: Source,
val title: String,
val url: String,
val urlToImage: String
)
SportNewsResponse.kt以下
数据类SportNewsResponse（val文章：列表，val状态：字符串，val totalResults：Int）
低于UseCaseResult.kt
sealed class UseCaseResult<out T : Any>() {
class Success<out T : Any>(val data: T) : UseCaseResult<T>()
class Error(val exception: Throwable) : UseCaseResult<Nothing>()
}
在实现了UserCaseResult的NewsRepository.kt下面
interface NewsRepository {
// Suspend is used to await
suspend fun getNewsList(): UseCaseResult<List<Article>>
}
@Suppress("UNCHECKED_CAST")
class NewsRepositoryImpl(private val sportsNewsApi: SportNewsInterface) : NewsRepository {
override suspend fun getNewsList(): UseCaseResult<List<Article>> {
return try {
val result = sportsNewsApi.getNewsAsync()
UseCaseResult.Success(result) as UseCaseResult<List<Article>>
} catch (ex: Exception) {
UseCaseResult.Error(ex)
}
}
}
在我的SportNewsInteface.kt下面
interface SportNewsInterface {
@GET("v2/top-headlines?country=us&apiKey=da331087e3f3462bb534b3b0917cbee9")
fun getNewsAsync(): Deferred<SportNewsResponse>
@GET("/v2/top-headlines?sources=espn&apiKey=da331087e3f3462bb534b3b0917cbee9")
fun getEspn(): Deferred<List<SportNewsResponse>>
@GET("/v2/top-headlines?sources=football-italia&apiKey=da331087e3f3462bb534b3b0917cbee9")
fun getFootballItalia(): Deferred<List<SportNewsResponse>>
@GET("/v2/top-headlines?sources=bbc-sport&apiKey=da331087e3f3462bb534b3b0917cbee9")
fun getBBCSport(): Deferred<List<SportNewsResponse>>
在我的服务器回应下面
{
"status": "ok",
"totalResults": 38,
"articles": [
{
"source": {
"id": "cnbc",
"name": "CNBC"
},
"author": "Holly Ellyatt",
"title": "Russia is now not the only pressing issue that NATO has to deal with - CNBC",
"description": "Heads of state and government are meeting in the U.K. this week for the 70th anniversary of the military alliance NATO.",
"url": "https://www.cnbc.com/2019/12/02/nato-summit-alliance-has-more-pressing-issues-than-russia-now.html",
"urlToImage": "https://image.cnbcfm.com/api/v1/image/106272467-1575218599700gettyimages-997112494.jpeg?v=1575218712",
"publishedAt": "2019-12-02T07:39:00Z",
"content": "US president Donald Trump is seen during his press conference at the 2018 NATO Summit in Brussels, Belgium on July 12, 2018.\r\nAs heads of state and government meet in the U.K. this week for the 70th anniversary of the military alliance NATO, discussions are l… [+8623 chars]"
},
{
"source": {
"id": null,
"name": "Chron.com"
},
"author": "Aaron Wilson",
"title": "Bill O'Brien gets game ball from Deshaun Watson after Texans' win over Patriots - Chron",
"description": "In an emotional moment, Texans coach Bill O'Brien was presented with the game ball by quarterback Deshaun Watson following a pivotal win over the New England Patriots.",
"url": "https://www.chron.com/sports/texans/article/Bill-O-Brien-Deshaun-Watson-Texans-Patriots-14874678.php",
"urlToImage": "https://s.hdnux.com/photos/01/07/23/50/18692664/3/rawImage.jpg",
"publishedAt": "2019-12-02T06:16:00Z",
"content": "<ul><li>Houston Texans head coach Bill O'Brien on the sidelines during the fourth quarter of an NFL game against the New England Patriots at NRG Stadium Sunday, Dec. 1, 2019, in Houston.\r\nHouston Texans head coach Bill O'Brien on the sidelines during the four… [+1583 chars]"
}
]
}