Android Livedata观察者Coroutine Kotlin

import androidx.lifecycle.LiveData
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import kotlinx.coroutines.launch

class MyViewModel : ViewModel() {
    private val _liveData = MutableLiveData<String>()
    val liveData: LiveData<String> get() = _liveData

    fun fetchData() {
        viewModelScope.launch {
            // 模拟网络请求或其他耗时操作
            val result = performLongRunningOperation()
            _liveData.value = result
        }
    }

    private suspend fun performLongRunningOperation(): String {
        // 模拟耗时操作
        delay(2000)
        return "Data fetched successfully"
    }
}

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.activity.viewModels
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {
    private val viewModel: MyViewModel by viewModels()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        viewModel.liveData.observe(this) { data ->
            textView.text = data
        }

        button.setOnClickListener {
            viewModel.fetchData()
        }
    }
}

viewModelScope.launch {
    try {
        val result = performLongRunningOperation()
        _liveData.value = result
    } catch (e: CancellationException) {
        // 协程被取消，处理异常
    }
}