Blank Screen Shows after search from database (Android)

Question

When i tap search donor then it shows blank screen in listview i don't know why This is the response that i get back from server

This is my custom adapter code:

package com.example.kamran.ebloodbank;

import android.app.Activity;
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.TextView;

import java.util.List;

/**
 * Created by Kamran on 4/12/2017.
 */

public class DonorAdapter extends BaseAdapter {

    private Activity activity;
    private LayoutInflater inflater;
    private List<DataSet> donorItems;

    public DonorAdapter(Activity activity,List<DataSet> donorItems) {
        this.activity = activity;
        this.donorItems = donorItems;

    }

    @Override
    public int getCount() {
        return donorItems.size();
    }

    @Override
    public Object getItem(int location) {
        return donorItems.get(location);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (inflater == null)
            inflater = (LayoutInflater) activity
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        if (convertView == null)
            convertView = inflater.inflate(R.layout.donor_search_list_theme, null);

        TextView nameTextView = (TextView) convertView.findViewById(R.id.donor_name);
        TextView areaTextView = (TextView) convertView.findViewById(R.id.donor_area);

        DataSet d = donorItems.get(position);

        nameTextView.setText(d.getName());
        areaTextView.setText(d.getArea());
        return convertView;
    }
}

This is my model code:

package com.example.kamran.ebloodbank;

import android.widget.ArrayAdapter;

import java.util.ArrayList;

/**
 * Created by Kamran on 4/12/2017.
 */

public class DataSet {
    private String name;
    private int area;


    public void setArea(int area) {
        this.area = area;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getArea() {
        return area;
    }

    public String getName() {
        return name;
    }


}

This is my first activity code:

package com.example.kamran.ebloodbank;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Spinner;

import com.android.volley.AuthFailureError;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import com.example.kamran.ebloodbank.data.BloodContract.BloodEntry;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class FindDonor extends AppCompatActivity {

    Spinner bloodgroup;
    Spinner area;
    String findDonorUrl = "https://wwwkamranalitk.000webhostapp.com/findDonor.php";
    int mBlood = BloodEntry.BLOOD_GROUP_A_POS;
    int mArea = BloodEntry.DONOR_AREA_MALIR;
    Button searchButton;
    RequestQueue requestQueue;
    StringRequest request;
    JSONObject jsonObject;
    JSONArray result;
    private List<DataSet> donorList = new ArrayList<DataSet>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_find_donor);


        bloodgroup = (Spinner) findViewById(R.id.bloodspinnerfinddonor);
        area = (Spinner) findViewById(R.id.areaSpinner);
        searchButton = (Button) findViewById(R.id.searchDonor);
        setupSpinnerBlood();
        setupSpinnerArea();
        requestQueue = Volley.newRequestQueue(getApplicationContext());

        searchButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                request = new StringRequest(Request.Method.POST, findDonorUrl, new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {

                            try {
                                jsonObject = new JSONObject(response);
                                result = jsonObject.getJSONArray("result");
                                JSONObject donorData = result.getJSONObject(0);
                                DataSet donorSet = new DataSet();

                                donorSet.setName(donorData.getString("name"));
                                donorSet.setArea(donorData.getInt("area"));
                                donorList.add(donorSet);
                                Intent intent = new Intent(FindDonor.this, DonorSearchList.class);

                                startActivity(intent);
                                finish();
                            } catch (JSONException e) {
                                e.printStackTrace();
                            }

                    }
                }, new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {

                    }
                }){
                    @Override
                    protected Map<String, String> getParams() throws AuthFailureError {
                        HashMap<String,String> parameters = new HashMap<String, String>();

                        parameters.put("bloodgroup", String.valueOf(mBlood));
                        parameters.put("area", String.valueOf(mArea));

                        return parameters;
                    }
                };

                requestQueue.add(request);
            }
        });

    }




    private void setupSpinnerBlood() {
        ArrayAdapter bloodGroupSpinnerAdapter = ArrayAdapter.createFromResource(this, R.array.blood_group, android.R.layout.simple_spinner_item);
        bloodGroupSpinnerAdapter.setDropDownViewResource(android.R.layout.simple_dropdown_item_1line);
        bloodgroup.setAdapter(bloodGroupSpinnerAdapter);

        bloodgroup.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                String selection = (String) parent.getItemAtPosition(position);
                if (!TextUtils.isEmpty(selection)) {
                    if (selection.equals(getString(R.string.blood_apos))) {
                        mBlood = BloodEntry.BLOOD_GROUP_A_POS;
                    } else if (selection.equals((getString(R.string.blood_bpos)))) {
                        mBlood = BloodEntry.BLOOD_GROUP_B_POS;
                    } else if (selection.equals(getString(R.string.blood_opos))) {
                        mBlood = BloodEntry.BLOOD_GROUP_O_POS;
                    } else if (selection.equals((getString(R.string.blood_oneg)))) {
                        mBlood = BloodEntry.BLOOD_GROUP_O_NEG;
                    }
                }
            }


            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {
                mBlood = BloodEntry.BLOOD_GROUP_A_POS;
            }
        });
    }

    private void setupSpinnerArea() {
        ArrayAdapter areaSpinnerAdapter = ArrayAdapter.createFromResource(this, R.array.area, android.R.layout.simple_spinner_item);
        areaSpinnerAdapter.setDropDownViewResource(android.R.layout.simple_dropdown_item_1line);
        area.setAdapter(areaSpinnerAdapter);

        area.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                String selection = (String) parent.getItemAtPosition(position);
                if (!TextUtils.isEmpty(selection)) {
                    if (selection.equals(getString(R.string.donor_area_malir))) {
                        mArea = BloodEntry.DONOR_AREA_MALIR;
                    } else if (selection.equals(getString(R.string.donor_area_defence))) {
                        mArea = BloodEntry.DONOR_AREA_DEFENCE;
                    } else if (selection.equals(getString(R.string.donor_area_korangi))) {
                        mArea = BloodEntry.DONOR_AREA_KORANGI;
                    } else if (selection.equals(getString(R.string.donor_area_johar))) {
                        mArea = BloodEntry.DONOR_AREA_JOHAR;
                    }
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {
                mArea = BloodEntry.DONOR_AREA_MALIR;
            }
        });

    }


}

and This is the code in which data will be shown:

package com.example.kamran.ebloodbank;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ListView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

public class DonorSearchList extends AppCompatActivity {

    private String mArea;
    private List<DataSet> donorList = new ArrayList<DataSet>();
    private ListView listView;
    private DonorAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_donor_search_list);

        listView = (ListView) findViewById(R.id.donorListView);
        adapter = new DonorAdapter(this, donorList);

        listView.setAdapter(adapter);



    }
}

Answer 1

You need to transfer data from the search to list activity. Try something like this:

public class bridge {
   public static List<DataSet> donorList = new ArrayList<DataSet>();
}

Then, in the class FindDonor:

donorSet.setName(donorData.getString("name"));
donorSet.setArea(donorData.getInt("area"));
donorList.add(donorSet);
//here put this line
bridge.donarList = donarList;
//rest code
Intent intent = new Intent(FindDonor.this, DonorSearchList.class);

Then, in the DonorSearchList class:

adapter = new DonorAdapter(this, bridge.donorList);