viewModelScope.在viewModel变量onDestory()不起作用的情况下启动

下面的coe只打印“onDestory”,而不是“launch”。但是,如果我像第二个块一样修改代码,那么就会打印“启动”。为什么?类成员变量是否在之前销毁 onDestroy() ?

  lateinit var viewModel: ArticleViewModel;

  override fun onCreate(savedInstanceState: Bundle?)
  {
    super.onCreate(savedInstanceState)
    viewModel = ViewModelProvider(this)[ArticleViewModel::class.java];
  ....

  override fun onDestroy()
  {
    super.onDestroy()
    Log.d("stack", "onDestroy");

    viewModel.viewModelScope.launch(Dispatchers.IO)
    {
      Log.d("stack", "launch");
    }
  }

修改

  override fun onDestroy()
  {
    super.onDestroy()
    Log.d("stack", "onDestroy");
    val vm = ViewModelProvider(this)[ArticleViewModel::class.java];
    vm.viewModelScope.launch(Dispatchers.IO)
    {
      Log.d("stack", "launch");
    }
  }