public class LifecycleDelegate implements LifecycleObserver {
  private LinkedList<Runnable> tasks = new LinkedList<>();
  private final LifecycleOwner lifecycleOwner;
  public LifecycleDelegate(LifecycleOwner lifecycleOwner) {
    this.lifecycleOwner = lifecycleOwner;
    lifecycleOwner.getLifecycle().addObserver(this);
  }
  public void scheduleTaskAtStarted(Runnable runnable) {
    if (getLifecycle().getCurrentState() != Lifecycle.State.DESTROYED) {
      assertMainThread();
      tasks.add(runnable);
      considerExecute();
    }
  }
  @OnLifecycleEvent(Lifecycle.Event.ON_ANY)
  void onStateChange() {
    if (getLifecycle().getCurrentState() == Lifecycle.State.DESTROYED) {
      tasks.clear();
      getLifecycle().removeObserver(this);
    } else {
      considerExecute();
    }
  }
  void considerExecute() {
    if (isAtLeastStarted()) {
      for (Runnable task : tasks) {
        task.run();
      }
      tasks.clear();
    }
  }
  boolean isAtLeastStarted() {
    return getLifecycle().getCurrentState().isAtLeast(Lifecycle.State.STARTED);
  }
  private Lifecycle getLifecycle() {
    return lifecycleOwner.getLifecycle();
  }
  private void assertMainThread() {
    if (!isMainThread()) {
      throw new IllegalStateException("you should perform the task at main thread.");
    }
  }
  static boolean isMainThread() {
    return Looper.getMainLooper().getThread() == Thread.currentThread();
  }
}

private LifecycleDelegate lifecycleDelegate = new LifecycleDelegate(this);