先执行然后操作

Question

我正在为我的应用程序构建一个小部件，以从Firestore获取一些数据。唯一的问题是，如果我可以将onDataSetChanged留空，那么最初可以在onCreate中成功获取数据。

我相信onDataSetChanged在一段时间后被操作系统调用以刷新。所以我不想将该功能留空。

但是问题是我无法在无限制递归的情况下导致onDataSetChanged中的窗口小部件更新，因为我正在使用notifyAppWidgetViewDataChanged刷新窗口小部件以显示从Firestore提取的新文档。

所以我的问题是，如何在我的Firebase查询的回调函数中不使用notifyAppWidgetViewDataChanged来刷新小部件？

谢谢

    public class TaskWidgetService extends RemoteViewsService {
   @Override
    public RemoteViewsFactory onGetViewFactory(Intent intent) {
        return new TaskWidgetItemFactory(getApplicationContext(), intent);
    }

    class TaskWidgetItemFactory implements RemoteViewsFactory {
        public static final String TAG = "TaskWidgetItemFactory";
        private Context context;
        private int appWidgetID;
        private ArrayList<String> tasksArrayList; //tasks I want to show

        public TaskWidgetItemFactory(Context context, Intent intent) {
            this.context = context;
            this.appWidgetID = intent.getIntExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, AppWidgetManager.INVALID_APPWIDGET_ID);
        }

        void initializeData() {

            Log.d(TAG, "initializeData: I'm being called.....");

            try {

                //Initialize ALL Firebase components
                FirebaseFirestore db = FirebaseFirestore.getInstance();
                FirebaseAuth mFirebaseAuth = FirebaseAuth.getInstance();
                String userId = mFirebaseAuth.getCurrentUser().getUid();

                final int a = this.appWidgetID;

                Query tasksQuery = db
                        .collection("users/" + userId + "/tasks")
                        .orderBy(Task.FIRESTORE_FIELD_DUE_TIMESTAMP, Query.Direction.ASCENDING)
                        .orderBy(Task.FIRESTORE_FIELD_PROGRESS, Query.Direction.ASCENDING)
                        .whereEqualTo(Task.FIRESTORE_FIELD_PARENT_TASK_DOC_ID, null) // only want Parent Tasks
                        ;

                tasksQuery.get()
                        .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {

                            @Override
                            public void onComplete(@NonNull com.google.android.gms.tasks.Task<QuerySnapshot> task) {
                                if (task.isSuccessful()) {
                                    for (QueryDocumentSnapshot document : task.getResult()) {
                                        Log.d(TAG, document.getId() + " => " + document.get("name"));

                                        Task t = document.toObject(Task.class);

                                        tasksArrayList.add(t.toString()); //add item to show
                                    }

                                    //refresh Widget to show the data.
                                    AppWidgetManager appWidgetManager = **AppWidgetManager.getInstance(context);
                                    appWidgetManager.notifyAppWidgetViewDataChanged(a, R.id.task_widget_stack_view);**

                                } else {
                                    Log.d(TAG, "Error getting documents: ", task.getException());
                                }
                            }
                        });

            } catch (Exception e) {
                Log.d(TAG, "initializeData: " + e.toString());
            }
        }

        @Override
        public void onCreate() {
            tasksArrayList = new ArrayList<>();
            initializeData();//get data
        }


       @Override
        public void onDataSetChanged() {

            tasksArrayList = new ArrayList<>();
            initializeData(); //get data  causes infinte recursion b/c of "notifyAppWidgetViewDataChanged"
        }


        @Override
        public int getCount() {
            Log.d(TAG, "getCount: " + tasksArrayList.size());
            return tasksArrayList.size();
        }

 }}

Answer 1

如果（您的清单！=空） {

yourList.clear（）;

先执行然后操作

}

最后您可以致电

adapter.notifydatasetChanged（）;

Answer 2

我能够通过使用await在onDataSetChnaged（）中获取数据来修复它。

@Override
        public void onDataSetChanged() {
            tasksArrayList = new ArrayList<>();

            FirebaseFirestore db = FirebaseFirestore.getInstance();
            FirebaseAuth mFirebaseAuth = FirebaseAuth.getInstance();
            String userId = mFirebaseAuth.getCurrentUser().getUid();

            Query tasksQuery = db
                    .collection("users/" + userId + "/tasks")
                    .orderBy(Task.FIRESTORE_FIELD_DUE_TIMESTAMP, Query.Direction.ASCENDING)
                    .orderBy(Task.FIRESTORE_FIELD_PROGRESS, Query.Direction.ASCENDING)
                    .whereEqualTo(Task.FIRESTORE_FIELD_PARENT_TASK_DOC_ID, null) // only want Parent Tasks
                    ;

            try {

                //wait for data to be collected.
                final QuerySnapshot querySnapshot = Tasks.await(tasksQuery.get());

                for (QueryDocumentSnapshot document : querySnapshot) {
                    Log.d(TAG, document.getId() + " => " + document.get("name"));

                    Task t = document.toObject(Task.class);
                    tasksArrayList.add(t);
                }

            } catch (ExecutionException e) {

                Toast.makeText(getApplicationContext(), "Failed to get Tasks.", Toast.LENGTH_LONG).show();

            } catch (InterruptedException e) {
                Toast.makeText(getApplicationContext(), "Failed to get Tasks.", Toast.LENGTH_LONG).show();

            }
        }

onDataSetChanged中的notifyAppWidgetViewDataChanged导致刷新吗？

2 个答案:

先执行然后操作