Ndtyjky

This is my TimeTableActivity.java, which displays listview of items(individual's schedules)

package com.example.jongha.meetingorganizer;



import android.content.Intent;

import android.os.Bundle;

import android.support.annotation.NonNull;

import android.support.annotation.Nullable;

import android.support.design.widget.FloatingActionButton;

import android.support.v7.app.AppCompatActivity;

import android.view.View;

import android.view.Window;

import android.widget.AdapterView;

import android.widget.ListView;



import com.google.firebase.database.ChildEventListener;

import com.google.firebase.database.DataSnapshot;

import com.google.firebase.database.DatabaseError;

import com.google.firebase.database.DatabaseReference;

import com.google.firebase.database.FirebaseDatabase;



import java.util.ArrayList;

import java.util.List;



public class TimeTableActivity extends AppCompatActivity {



private FloatingActionButton addScheduleBtn;



DatabaseReference dref;

ListView listview;





@Override

protected void onCreate(@Nullable Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_timetable);



    //listview 연결, adapter 생성과 연결, dref연결

    listview=(ListView)findViewById(R.id.schedule_list_view);

    final ScheduleListViewAdapter adapter = new ScheduleListViewAdapter();

    listview.setAdapter(adapter);

    dref = FirebaseDatabase.getInstance().getReference("timetables/test1999");

    //dref change to path of logged-in user하기





    //realtime database 데이터 변화에 대한 반응

    dref.addChildEventListener(new ChildEventListener() {

        @Override

        public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

            adapter.addItem(dataSnapshot.getValue(ScheduleDTO.class));

            adapter.notifyDataSetChanged();

        }



        @Override

        public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {



        }



        @Override

        public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {

            adapter.removeItem(dataSnapshot.getValue(ScheduleDTO.class));

            adapter.notifyDataSetChanged();

        }



        @Override

        public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {



        }



        @Override

        public void onCancelled(@NonNull DatabaseError databaseError) {



        }

    });





    //listview의 스케쥴 각각에 대한 onclicklistner



    listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        @Override

        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

            ScheduleDTO item = (ScheduleDTO) parent.getItemAtPosition(position);



            Intent intent = new Intent(TimeTableActivity.this, DisplayScheduleActivity.class);

            String infoOfSchedule = new String {item.getActivityName(), item.getStartHour(), item.getStartMin(), item.getEndHour(), item.getEndMin(), item.getDayOfWeek()};

            intent.putExtra("dataStrings", infoOfSchedule);

            startActivity(intent);

        }

    });





    //스케쥴 추가 버튼 onclicklistner

    addScheduleBtn = findViewById(R.id.add_schedule_btn);

    addScheduleBtn.setOnClickListener(new View.OnClickListener(){

        @Override

        public void onClick(View v) {

            startActivity(new Intent(TimeTableActivity.this, NewScheduleActivity.class));

        }

    });

}

}

and this is my custom listview adapter, ScheduleListViewAdapter.java

package com.example.jongha.meetingorganizer;



import android.content.Context;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.BaseAdapter;

import android.widget.TextView;



import java.util.ArrayList;



public class ScheduleListViewAdapter extends BaseAdapter {





private ArrayList<ScheduleDTO> listViewItemList = new ArrayList<ScheduleDTO>();



//ScheduleListViewAdapter 생성

public ScheduleListViewAdapter() {

}



@Override

public int getCount() {

    return listViewItemList.size();

}



@Override

public Object getItem(int position) {

    return listViewItemList.get(position);

}



@Override

public long getItemId(int position) {

    return position;

}



@Override

public View getView(int position, View convertView, ViewGroup parent) {

    final int pos = position;

    final Context context = parent.getContext();



    // "layout_schedule_listview.xml" Layout을 inflate하여 convertView 참조 획득.

    if (convertView == null) {

        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        convertView = inflater.inflate(R.layout.layout_schedule_listview, parent, false);

    }



    // 화면에 표시될 View(Layout이 inflate된)으로부터 위젯에 대한 참조 획득

    TextView titleTextView = (TextView) convertView.findViewById(R.id.scheduleListNameView) ;

    TextView timeTextView = (TextView) convertView.findViewById(R.id.scheduleListTimeView) ;



    // Data Set(listViewItemList)에서 position에 위치한 데이터 참조 획득

    ScheduleDTO listViewItem = listViewItemList.get(position);



    // 아이템 내 각 위젯에 데이터 반영

    titleTextView.setText(listViewItem.getActivityName());

    timeTextView.setText(listViewItem.getListViewTime());



    return convertView;

}



public void addItem(ScheduleDTO gotItem) {

    listViewItemList.add(gotItem);

}



public void removeItem(ScheduleDTO gotItem){

    listViewItemList.remove(gotItem);

}

}

My problem is that though delete function being called in other activity is running correctly(deleting data in firebase console), and listview is well-updated after TimeTableActivity being called again after TimeTableActivity being finished, listview is not being updated properly right after deleting item.

In fact, i had a typo in TimetableActivity.java at first.
I typed
adapter.addItem(....) instead of adapter.removeItem(....) in onChlidRemoved method.
In this situation, listview was updated, containing two same item.
For example, if i had item A and it being deleted, listview was immediately updated and displaying two A.
However, after changing to adapter.removeItem(...), listview is not being updated immediately after deleting item.

How should i fix this problem??