ViewModelScope.launch启动的协程是运行在主线程的。
ComponentActivity会用Lifecycle注册生命周期事件，当Activity销毁的时候，会调用ViewModel的clear()方法:
getLifecycle().addObserver(new LifecycleEventObserver() {
@Override
public void onStateChanged(@NonNull LifecycleOwner source,
@NonNull Lifecycle.Event event) {
if (event == Lifecycle.Event.ON_DESTROY) {
if (!isChangingConfigurations()) {
getViewModelStore().clear();
}
}
}
});
/**
* Check to see whether this activity is in the process of being destroyed in order to be
* recreated with a new configuration. This is often used in
* {@link #onStop} to determine whether the state needs to be cleaned up or will be passed
* on to the next instance of the activity via {@link #onRetainNonConfigurationInstance()}.
*
* @return If the activity is being torn down in order to be recreated with a new configuration,
* returns true; else returns false.
*/
public boolean isChangingConfigurations() {
return mChangingConfigurations;
}
ViewModelStore的clear()方法会调用ViewModel真正的clear方法
/**
* Clears internal storage and notifies ViewModels that they are no longer used.
*/
public final void clear() {
for (ViewModel vm : mMap.values()) {
vm.clear();
}
mMap.clear();
}
