Apps ListView is not getting displayed on selecting an item from spinner

[shikher mishra]

I am creating two spinners: One for City and the other for Area in that particular city. As per the selection made by the user in the above spinners, a ListView will be displayed which will be different for different combinations of selections made by the user in spinners.I am fetching the data for the Listview from the database stored in the Firebase.The URL mentioned in the java code would change everytime.But the listview itself is not getting displayed.

The layout which has the spinners and the listview is as follows:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:eek:rientation="vertical" android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:paddingTop="100dp"
   >
   <TextView
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="Select a City"
       />

   <Spinner
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:id="@+id/selectCity"
       android:entries="[USER=747843]@array[/USER]/city_name"
       android:textSize="20sp"
       android:singleLine="false"
       android:prompt="[USER=696546]@String[/USER]/city_title"
       android:eek:utlineProvider="background"

       android:background="@android:drawable/btn_dropdown"
       />
   <TextView
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="Select Area"
       android:paddingTop="20sp"
       />
   <Spinner
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:id="@+id/select_area"
       android:background="@android:drawable/btn_dropdown"
       >
   </Spinner>
   <ListView
       android:layout_width="match_parent"
       android:layout_height="wrap_content"

       android:id="@+id/displayAllAstrologers"

       ></ListView>

</LinearLayout>

The java fragment code through which I am handling spinners and Listview are:

package com.example.hsports.weddingplanner.Fragments;

   import android.content.Context;
   import android.content.Intent;
   import android.content.SharedPreferences;
   import android.os.Bundle;
   import android.support.annotation.Nullable;
   import android.support.v4.app.Fragment;
   import android.view.LayoutInflater;
   import android.view.View;
   import android.view.ViewGroup;
   import android.widget.AdapterView;
   import android.widget.ArrayAdapter;
   import android.widget.ListView;
   import android.widget.Spinner;

   import com.example.hsports.weddingplanner.Activities.FrontPage;
   import com.example.hsports.weddingplanner.Adapters.displayingListCategories;
   import com.example.hsports.weddingplanner.R;
   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 com.google.firebase.database.ValueEventListener;

   import java.util.ArrayList;

   /**
    * Created by I324671 on 12/5/2016.
    */
   public class Location_Selection extends Fragment {
       ArrayList<String> listCategories=new ArrayList<>();

       String categorySelected;

       String citySelected="";
       String areaSelected="";
       public  Location_Selection(String categorySelected)
       {
           this.categorySelected= this.categorySelected;
       }
       @Nullable
       [USER=1021285]@override[/USER]
       public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
           View view=inflater.inflate(R.layout.city_selection_page,container,false);
           final Spinner areaSelector=(Spinner)view.findViewById(R.id.select_area);
           Spinner selectCity=(Spinner)view.findViewById(R.id.selectCity);
           final ListView listView = (ListView) view.findViewById(R.id.displayAllAstrologers);
          selectCity.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
              [USER=1021285]@override[/USER]
              public void onItemSelected(AdapterView<?> parent, final View view, int position, long id) {

                  final ArrayList<String> listAreas = new ArrayList<String>();

                  String s = parent.getItemAtPosition(position).toString();
                  FirebaseDatabase database = FirebaseDatabase.getInstance();
                  DatabaseReference reference = database.getReference(s);

                  reference.addValueEventListener(new ValueEventListener() {
                      [USER=1021285]@override[/USER]
                      public void onDataChange(DataSnapshot dataSnapshot) {

                          if (dataSnapshot.hasChildren()) {
                              for (DataSnapshot child : dataSnapshot.getChildren()) {
                                  String areaId = child.getKey().toString();
                                  String areaName = child.getValue().toString();
                                  listAreas.add(areaName);
                              }
                          }
                          ArrayAdapter<String> adapter = new ArrayAdapter(view.getContext(),
                                  android.R.layout.simple_spinner_item, listAreas);
   adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
                          areaSelector.setAdapter(adapter);
                      }
                      [USER=1021285]@override[/USER]
                      public void onCancelled(DatabaseError databaseError) {
                      }
                  });

              }
              [USER=1021285]@override[/USER]
              public void onNothingSelected(AdapterView<?> parent) {

              }
          });
           areaSelector.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
               [USER=1021285]@override[/USER]
               public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                   FirebaseDatabase database1 = FirebaseDatabase.getInstance();
                   DatabaseReference reference1 = database1.getReference("Astrologer-Hoodi/email");
                   reference1.addValueEventListener(new ValueEventListener() {
                       [USER=1021285]@override[/USER]
                       public void onDataChange(DataSnapshot dataSnapshot) {

                           if (dataSnapshot.hasChildren()) {
                               for (DataSnapshot child : dataSnapshot.getChildren()) {
                                   String getEmailNo = child.getKey().toString();
                                   String getEmailId = child.getValue().toString();
                                   listCategories.add(getEmailId);
                               }
                           }
listView.setAdapter(new displayingListCategories(getContext(), listCategories));
                       }
                       [USER=1021285]@override[/USER]
                       public void onCancelled(DatabaseError databaseError) {
                       }

                   });



               }

               [USER=1021285]@override[/USER]
               public void onNothingSelected(AdapterView<?> parent) {

               }
           });

           return  view;
       }
          }

I am using a baseAdapter to inflate the ListView in the xml. So the Adapter clas which extends BaseAdapter is as follows:

package com.example.hsports.weddingplanner.Adapters;

import android.content.Context;
import android.database.Cursor;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.CursorAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import com.example.hsports.weddingplanner.R;
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 com.google.firebase.database.ValueEventListener;

import java.util.ArrayList;

/**
* Created by I324671 on 12/5/2016.
*/
public class displayingListCategories extends BaseAdapter {

   private Context mcontext;

   public ArrayList<String> listCategories;

   public displayingListCategories(Context context,ArrayList<String> listCategories) {
       //super(context, c);
       mcontext=context;
       this.listCategories=listCategories;
   }


   [USER=1021285]@override[/USER]
   public int getCount() {
       return 0;
   }

   [USER=1021285]@override[/USER]
   public Object getItem(int position) {
       return null;
   }

   [USER=1021285]@override[/USER]
   public long getItemId(int position) {
       return 0;
   }

   [USER=1021285]@override[/USER]
   public View getView(int position, View convertView, ViewGroup parent) {

       View view= LayoutInflater.from(convertView.getContext()).inflate(R.layout.format_of_list_of_categories, parent, false);
       ImageView imageView=(ImageView)view.findViewById(R.id.image_of_customer);
       imageView.setImageResource(R.drawable.customer_photo);
       TextView nameOfCustomer=(TextView)view.findViewById(R.id.name_of_customer);
       TextView emailIdOfCustomer=(TextView)view.findViewById(R.id.email_id_of_customer);
       TextView phoneOfCustomer=(TextView)view.findViewById(R.id.phone_no_of_customer);
       nameOfCustomer.setText(listCategories.get(position));
       emailIdOfCustomer.setText(listCategories.get(position));
       phoneOfCustomer.setText(listCategories.get(position));
           return view;
   }
}

I am not getting the listview displayed. And I want the listview to be different for different selections in the spinners.

 

[Unforgiven]

Welcome to AndroidForums.com.

I moved your thread here as folks in the Application Development area will be more likely able to help. I also added code tags to your post to make the syntax easier to read. Good luck.

 

[Deleted User]

The first obvious thing that occurs to me is that your spinner onItemSelected method creates a new instance of the list adapter every single time it's called. This is inefficient. You should set the list adapter only once, and if the list of items changes, call adapter.notifyDataSetChanged()

 

[shikher mishra]

The first obvious thing that occurs to me is that your spinner onItemSelected method creates a new instance of the list adapter every single time it's called. This is inefficient. You should set the list adapter only once, and if the list of items changes, call adapter.notifyDataSetChanged()

But why my ListView is not getting displayed? It should display atleast once in the view.

 

[Deleted User]

Because your ListView adapter doesn't even get set until an item in the spinner is selected, then that could be causing a problem. Setting the ListView adapter should be one of the first things that happens in onCreateView().