java.lang.IllegalStateException 오류 해결하기

아래와 같은 오류가 나타났다. 스레드가 백스라운드에서 값이 변경되려고 해서 그런다고 한다.

 

E/AndroidRuntime: FATAL EXCEPTION: DefaultDispatcher-worker-1
    Process: com.myungwoo.gettiming_app, PID: 30214
    java.lang.IllegalStateException: Cannot invoke setValue on a background thread
        at androidx.lifecycle.LiveData.assertMainThread(LiveData.java:487)
        at androidx.lifecycle.LiveData.setValue(LiveData.java:306)
        at androidx.lifecycle.MutableLiveData.setValue(MutableLiveData.java:50)
        at com.myungwoo.gettiming_app.viewModel.SelectViewModel$saveSelectedCoinList$1.invokeSuspend(SelectViewModel.kt:90)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
        at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:106)
        at kotlinx.coroutines.internal.LimitedDispatcher.run(LimitedDispatcher.kt:42)
        at kotlinx.coroutines.scheduling.TaskImpl.run(Tasks.kt:95)
        at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:570)
        at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:750)
        at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:677)
        at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:664)
     Suppressed: kotlinx.coroutines.DiagnosticCoroutineContextException: [StandaloneCoroutine{Cancelling}@7a89ce3, Dispatchers.IO]

 

 

해결방법은 아래와 같다. 오류난 부분을 withContext(Dispatchers.Main){ } 이걸로 감싸주면 끝!

 

< 코드 >

withContext(Dispatchers.Main){
    _save.value = "done"
}