因为我是Android编程的新手。当我点击button中的AlertDialog现状，缺席或延迟时，ListView会在列表中再次将List<String>的所有相同值添加到listView并显示它。而不是这样做我想只将数据发送到Firebase并更新地图值。我尝试了所有方法来删除此错误，但我无法找到问题。我想删除这个bug。请帮助我摆脱这个问题。
以下是代码：
public class Tab1 extends android.support.v4.app.Fragment {
Context context;
FirebaseDatabase firebaseDatabase = FirebaseDatabase.getInstance ();
DatabaseReference databaseReference = firebaseDatabase.getReference ();
private JazzyListView listView;
int check=0, connection =0;
Map map = new HashMap ();
Vibrator vibrator;
public static MyAdapter adapter;
ProgressDialog progressDialog;
List<String> ListString = new ArrayList<> ();
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate (R.layout.fragment_tab1, container, false);
context = getContext ();
Log.e ("Length", String.valueOf (map.size ()));
vibrator = (Vibrator) getActivity ().getSystemService (Context.VIBRATOR_SERVICE);
adapter = new MyAdapter (context, ListString);
final PullRefreshLayout pullToRefreshView=(PullRefreshLayout) view.findViewById (R.id.pull);
final Connectivity connectivity = new Connectivity (context);
pullToRefreshView.setRefreshStyle (PullRefreshLayout.STYLE_WATER_DROP);
pullToRefreshView.setOnRefreshListener (new PullRefreshLayout.OnRefreshListener () {
@Override
public void onRefresh() {
if(!connectivity.isConnected ()){
Toast.makeText (context, "Connectivity to database lost. Kindly try again later or Connect your device to Internet", Toast.LENGTH_LONG).show ();
ListString.clear ();
pullToRefreshView.setRefreshing (false);
}else {
ListString.clear ();
progressDialog = new ProgressDialog (context);
progressDialog.setCancelable (false);
progressDialog.setIcon (R.drawable.ic_file_download_black_24dp);
progressDialog.setMessage ("Hold your Patience");
progressDialog.setTitle ("Updating");
progressDialog.show ();
databaseReference.addValueEventListener (new ValueEventListener () {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
DataSnapshot snapshot = dataSnapshot.child ("User");
for(DataSnapshot s: snapshot.getChildren ()) {
if (s.getValue ().toString ().isEmpty ())
Toast.makeText (context, "Empty", Toast.LENGTH_SHORT).show ();
else
ListString.add (s.getKey ().toString ());
}
adapter.notifyDataSetChanged ();
progressDialog.dismiss ();
pullToRefreshView.setRefreshing (false);
}
@Override
public void onCancelled(DatabaseError databaseError) {
Toast.makeText (context, databaseError.getMessage (), Toast.LENGTH_SHORT).show ();
}
});
}
}
});
if(connectivity.isConnected () || connection==1){
progressDialog = new ProgressDialog (context);
progressDialog.setCancelable (false);
progressDialog.setIcon (R.drawable.ic_file_download_black_24dp);
progressDialog.setMessage ("Hold your Patience");
progressDialog.setTitle ("Retrieving Data");
progressDialog.show ();
ListString.add ("Adding");
databaseReference.addValueEventListener (new ValueEventListener () {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
check++;
if(check<=1) {
ListString.remove ("Adding");
DataSnapshot snapshot = dataSnapshot.child ("User");
for(DataSnapshot s: snapshot.getChildren ())
{
if(s.getValue ().toString ().isEmpty ())
Toast.makeText (context, "Empty", Toast.LENGTH_SHORT).show ();
else
ListString.add(s.getKey ().toString ());
}
progressDialog.dismiss ();
adapter.notifyDataSetChanged ();
}else{
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
Toast.makeText (context, databaseError.getMessage (), Toast.LENGTH_SHORT).show ();
}
});
}else{
AlertDialog.Builder builder = new AlertDialog.Builder (context);
builder.setTitle("No Network")
.setMessage ("No Network Available").setPositiveButton ("Try again", new DialogInterface.OnClickListener () {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
vibrator.vibrate (100);
if(connectivity.isConnected ())
connection=1;
else
Toast.makeText (context, "No Connection", Toast.LENGTH_SHORT).show ();
}
}).setNeutralButton ("Ok", new DialogInterface.OnClickListener () {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
dialogInterface.dismiss ();
vibrator.vibrate (100);
}
}).setIcon (R.drawable.nowifi);
AlertDialog alertDialog = builder.create ();
alertDialog.show ();
}
listView = (JazzyListView) view.findViewById (R.id.listview);
listView.setTransitionEffect (new FadeEffect ());
listView.setAdapter (adapter);
//adapter.notifyDataSetChanged ();
listView.setOnItemClickListener (new AdapterView.OnItemClickListener () {
@Override
public void onItemClick(final AdapterView<?> adapterView, final View view, final int postion, long l) {
adapter.count = 0;
final String itemname = adapterView.getItemAtPosition (postion).toString ();
try{
AlertDialog.Builder builder = new AlertDialog.Builder (context);
builder.setTitle("Attendence Tick")
.setMessage (itemname).setPositiveButton ("Present", new DialogInterface.OnClickListener () {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
try{
Calendar calendar = Calendar.getInstance ();
SimpleDateFormat simpleDateFormat = new SimpleDateFormat ("dd MMM yyyy");
DatabaseReference user = databaseReference.child ("Attendence");
DatabaseReference date = user.child (simpleDateFormat.format (calendar.getTime ()));
DatabaseReference name = date.child (itemname);
name.setValue ("Present");
vibrator.vibrate (100);
map.put (String.valueOf (postion), "1");
adapter.setPresent (map);
adapter.notifyDataSetChanged ();
}catch (Exception e){
Log.e ("Problem", e.getMessage ());
}
}
}).setNeutralButton ("Absent", new DialogInterface.OnClickListener () {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
Calendar calendar = Calendar.getInstance ();
SimpleDateFormat simpleDateFormat = new SimpleDateFormat ("dd MMM yyyy");
DatabaseReference user = databaseReference.child ("Attendence");
DatabaseReference date = user.child (simpleDateFormat.format (calendar.getTime ()));
DatabaseReference name = date.child (itemname);
name.setValue ("Absent");
vibrator.vibrate (100);
map.put (String.valueOf (postion), "0");
adapter.setPresent (map);
adapter.notifyDataSetChanged ();
}
}).setNegativeButton ("Late", new DialogInterface.OnClickListener () {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
Calendar calendar = Calendar.getInstance ();
SimpleDateFormat simpleDateFormat = new SimpleDateFormat ("dd MMM yyyy");
DatabaseReference user = databaseReference.child ("Attendence");
DatabaseReference date = user.child (simpleDateFormat.format (calendar.getTime ()));
DatabaseReference name = date.child (itemname);
name.setValue ("Late");
vibrator.vibrate (100);
map.put (String.valueOf (postion), "2");
adapter.setPresent (map);
adapter.notifyDataSetChanged ();
}
}).setIcon (R.drawable.ic_done_all_white_24dp);
AlertDialog alertDialog = builder.create ();
alertDialog.show ();
}catch (Exception e){
Toast.makeText (context, e.getMessage (), Toast.LENGTH_SHORT).show ();
}
}
});
return view;
}
}
答案 0 :(得分：0)
**Place this when you add item to arraylist, to avoid duplication**
if(ListString.size>0){
if(!ListString.contians(s.getKey ().toString ()){
ListString.add(s.getKey ().toString ());
}
}else{
ListString.add(s.getKey ().toString ());
}