Question

试图进行大量搜索，但是两天后，我仍然对这个问题感到困惑。我的Firebase中有以下数据库，该数据库填充在我的def create calendar_id = params[:calendar][:id] start_date = params[:calendar][:start_date] start_time = params[:calendar][:start_time] time_zone = params[:calendar][:time_zone] lesson_hash = get_module_lectures(module_number) # Time.zone = 'America/New_York' lesson_hash.each do |days_from_start, lesson_name| lesson_datetime = Time.parse("#{start_date} #{start_time}").advance(:days => days_from_start) new_event(calendar_id, lesson_datetime, lesson_name, time_zone) end redirect_to calendars_url end def new_event(calendar_id, lesson_datetime, lesson_name, time_zone) client = Signet::OAuth2::Client.new(client_options) client.update!(session[:authorization]) service = Google::Apis::CalendarV3::CalendarService.new service.authorization = client event = Google::Apis::CalendarV3::Event.new({ # start: Google::Apis::CalendarV3::EventDateTime.new(datetime: lesson_datetime), # end: Google::Apis::CalendarV3::EventDateTime.new(datetime: lesson_datetime.advance(:hours => 1)), start: { 'date_time': lesson_datetime, # 'time_zone': 'America/New_York' }, end:{ 'date_time': lesson_datetime.advance(:hours => 1), # 'time_zone': 'America/New_York' }, summary: lesson_name }) service.insert_event(calendar_id, event) end中。对于ListView中的每一行，都会显示data1和data2。

ListView

直到现在一切顺利，我可以从应用程序上传数据，并且列表视图与Firebase控制台完全同步。

我使用以下代码制作了ListView：

 test-3db7e
  |
  +---users
       |
       +---W9KkXAidmHgyOpyeQPeT5YxgQI42
            |
            +---data
            |    |
            |    +----LIv-OeQdixT0q6NZ-jL
            |    |     |
            |    |     +---data1: "Data1"
            |    |     |
            |    |     +---data2: "Data2"
            |    |
            |    +----LIv-R3PRKaEHaAcMjWu
            |          |
            |          +---data1: "Data1"
            |          |
            |          +---data2: "Data2"
            |
            +---name: "The user's name"

我还创建了Data.class来将先前代码中的值存储到列表视图中。

    //Updating the listview
    databaseReference.child("users").child(user).child("data").addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

            //Getting all the children at this level
            Iterable<DataSnapshot> children = dataSnapshot.getChildren();
            dataArrayAdapter.clear();

            for (DataSnapshot child : children) {

                Data data = child.getValue(Data.class);
                dataList.add(data);
                dataArrayAdapter.notifyDataSetChanged();

            }
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });

现在的问题是以下代码，长按要删除的行（如果在对话框中按是），长按要删除的行。

    package com.mypackge.firebase;

    public class Data {

        private String data1;
        private String data2;

        public String getData1() {
            return data1;
        }

        public void setData1(String data1) {
            this.data1 = data1;
        }

        public String getData2() {
            return data2;
        }

        public void setData2(String data2) {
            this.data2 = data2;
        }

        public String toString() {
            return data1 +"\n"+data2;
        }
    }

谢谢大家的宝贵时间！

Answer 1

解决此问题的关键是将创建pushed key类的对象时生成的Data添加到数据库中。因此，在data1和data2字段旁边，添加另一个名为key（也是String类型）的字段。请同时为该新字段添加相应的setter和getter。

现在，这是实际上需要在对象上创建的方式：

DatabaseReference dataRef = databaseReference.child("users").child(user).child("data");
String key = dataRef.push().getKey();
Data data = new Data();
data.setData1("data1");
data.setData2("data2");
data.setKey(key);
dataRef.child(key).setValue(data);

现在，您的Data对象的key字段中填充了数据库中的实际密钥。要显示数据并删除单击的特定对象，请使用以下代码：

ValueEventListener valueEventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        ArrayList<Data> list = new ArrayList<>();
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            Data data = ds.getValue(Data.class);
            list.add(data);
        }
        ListView listView = (ListView) findViewById(R.id.list_view);
        ArrayAdapter<Data> arrayAdapter = new ArrayAdapter<>(getApplicationContext(), android.R.layout.simple_list_item_1, list);
        listView.setAdapter(arrayAdapter);

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                AlertDialog.Builder builder = new AlertDialog.Builder(getApplicationContext());
                builder.setMessage("Do you want to delete?");

                builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int i) {
                        String key = arrayAdapter.getItem(i).getKey();
                        dataRef.child(key).removeValue();
                    }
                });

                builder.setNegativeButton("No", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int i) {
                        dialog.dismiss();
                    }
                });

                AlertDialog dialog = builder.create();
                dialog.show();
            }
        });
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {}
};
dataRef.addListenerForSingleValueEvent(valueEventListener);

长按上的ListView中的Firebase Android删除节点键

1 个答案: