Expandable List View with JSON

Question

Hey I am trying to get data from my database and show it on an ExpandableListView. The application keeps on crashing when I started using JSON but before that it worked fine.

my adapter class

public class ExpandableListAdapterA extends BaseExpandableListAdapter 
{

private Activity context;
private Map<String, List<String>> laptopCollections;
private List<String> laptops;

public ExpandableListAdapterA(Activity context, List<String> laptops,
        Map<String, List<String>> laptopCollections) {
    this.context = context;
    this.laptopCollections = laptopCollections;
    this.laptops = laptops;
}

public Object getChild(int groupPosition, int childPosition) {
    return laptopCollections.get(laptops.get(groupPosition)).get(childPosition);
}

public long getChildId(int groupPosition, int childPosition) {
    return childPosition;
}

public View getChildView(final int groupPosition, final int childPosition,
        boolean isLastChild, View convertView, ViewGroup parent) {
    final String laptop = (String) getChild(groupPosition, childPosition);
    LayoutInflater inflater = context.getLayoutInflater();

    if (convertView == null) {
        convertView = inflater.inflate(R.layout.child_view, null);
    }

    TextView item = (TextView) convertView.findViewById(R.id.laptop);

    ImageView delete = (ImageView) convertView.findViewById(R.id.delete);
    delete.setOnClickListener(new OnClickListener() {

        public void onClick(View v) {
            AlertDialog.Builder builder = new AlertDialog.Builder(context);
            builder.setMessage("Do you want to remove?");
            builder.setCancelable(false);
            builder.setPositiveButton("Yes",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            List<String> child =
                                laptopCollections.get(laptops.get(groupPosition));
                            child.remove(childPosition);
                            notifyDataSetChanged();
                        }
                    });
            builder.setNegativeButton("No",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            dialog.cancel();
                        }
                    });
            AlertDialog alertDialog = builder.create();
            alertDialog.show();
        }
    });

    item.setText(laptop);
    return convertView;
}

public int getChildrenCount(int groupPosition) {
    return laptopCollections.get(laptops.get(groupPosition)).size();
}

public Object getGroup(int groupPosition) {
    return laptops.get(groupPosition);
}

public int getGroupCount() {
    return laptops.size();
}

public long getGroupId(int groupPosition) {
    return groupPosition;
}

public View getGroupView(int groupPosition, boolean isExpanded,
        View convertView, ViewGroup parent) {
    String laptopName = (String) getGroup(groupPosition);
    if (convertView == null) {
        LayoutInflater infalInflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = infalInflater.inflate(R.layout.parent_view,
                null);
    }
    TextView item = (TextView) convertView.findViewById(R.id.head);
    item.setTypeface(null, Typeface.BOLD);
    item.setText(laptopName);
    return convertView;
}

public boolean hasStableIds() {
    return true;
}

public boolean isChildSelectable(int groupPosition, int childPosition) {
    return true;
}
 }

my other class

public class Product extends Activity {

List<String> groupList;
List<String> childList;
Map<String, List<String>> laptopCollection;
ExpandableListView expListView;
private static String url = "http://10.0.2.2/Monoprix/DB_Connect.php";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.products);

    new createGroupList().execute();



    expListView = (ExpandableListView) findViewById(R.id.products);
    final ExpandableListAdapter expListAdapter = new ExpandableListAdapterA(this, groupList, laptopCollection);
    expListView.setAdapter(expListAdapter);

    //setGroupIndicatorToRight();

    expListView.setOnChildClickListener(new OnChildClickListener() {

        public boolean onChildClick(ExpandableListView parent, View v,
                int groupPosition, int childPosition, long id) {
            final String selected = (String) expListAdapter.getChild(
                    groupPosition, childPosition);
            Toast.makeText(getBaseContext(), selected, Toast.LENGTH_LONG)
                    .show();

            return true;
        }
    });
}



class createGroupList extends AsyncTask<String,String,String> {
    protected String doInBackground(String... args) {
    groupList = new ArrayList<String>();
    String[] hpModels = { "HP Pavilion G6-2014TX", "ProBook HP 4540",
    "HP Envy 4-1025TX" };

    //String[] lenovoModels = { "IdeaPad Z Series", "Essential G Series","ThinkPad X Series", "Ideapad Z Series" };
    String[] dellModels = { "Inspiron", "Vostro", "XPS" };
    try{
        JSONParser jsonParser = new JSONParser();
        JSONObject json = jsonParser.getJSONFromUrl(url);
        Log.d("Create Response", json.toString());
        JSONArray title = json.getJSONArray("product");
        for (int i=0;i<title.length();i++)
        {
            JSONObject c = title.getJSONObject(i);
            String categ = c.getString("product_category");
            groupList.add(categ);
        }
        childList = new ArrayList<String>();
        laptopCollection = new LinkedHashMap<String, List<String>>();
        for (String laptop : groupList) {
            if (laptop.equals("HP")) {
                for ( String model : hpModels)
                    childList.add(model);
            } else if (laptop.equals("Dell"))
                for (String model : dellModels )
                    childList.add(model);

            laptopCollection.put(laptop, childList);
        }

 }catch (JSONException e)
{
    e.printStackTrace();
}
    return null;
    }
}


public int getDipsFromPixel(float pixels) {
    // Get the screen's density scale
    final float scale = getResources().getDisplayMetrics().density;
    // Convert the dps to pixels, based on density scale
    return (int) (pixels * scale + 0.5f);
}
 }

XML files xml page that contain the expandablelist products.xml

<ExpandableListView
    android:id="@+id/products"
    android:layout_width="match_parent"
    android:layout_height="fill_parent" >
</ExpandableListView>

parent_view.xml

<TextView
    android:id="@+id/head"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:paddingLeft="25dp"/>

child_view.xml

<TextView
    android:id="@+id/laptop"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_centerVertical="true"
    android:paddingLeft="25dp" />

<ImageView
    android:id="@+id/delete"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentRight="true"
    android:contentDescription="@string/app_name"
    android:src="@drawable/ic_delete" />

Answer 1

please try it and kindly change getapplicationcontext() instead of getactivity() and change oncreate for Activity

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

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

    import android.app.Fragment;
    import android.app.ProgressDialog;
    import android.content.Intent;
    import android.os.AsyncTask;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.ExpandableListAdapter;
    import android.widget.ExpandableListView;
    import android.widget.ExpandableListView.OnChildClickListener;
    import android.widget.ExpandableListView.OnGroupClickListener;
    import android.widget.ExpandableListView.OnGroupCollapseListener;
    import android.widget.ExpandableListView.OnGroupExpandListener;
    import android.widget.TextView;
    import android.widget.Toast;

    public class HomeFragment extends Fragment {
        private static String url = "http://www.androidbegin.com/tutorial/jsonparsetutorial.txt";
        private ProgressDialog mprocessingdialog;
        private TextView tv_welcomeuser, tv_recentupdate;
        private ExpandableListAdapter expandableListAdapter;
        private ExpandableListView exp_leaseoffer;
        private List<String> listDataHeader;
        private View rootView;
        private HashMap<String, List<String>> listDataChild;

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {

            rootView = inflater.inflate(R.layout.wellcome_page, container, false);
            tv_welcomeuser = (TextView) rootView.findViewById(R.id.tv_welcomeuser);
            tv_recentupdate = (TextView) rootView
                    .findViewById(R.id.tv_recentupdate);

            exp_leaseoffer = (ExpandableListView) rootView.findViewById(R.id.lvExp);

            new DownloadJason().execute();

            return rootView;
        }

        private class DownloadJason extends AsyncTask<Void, Void, Void> {

            @Override
            protected void onPreExecute() {
                // TODO Auto-generated method stub
                super.onPreExecute();
                mprocessingdialog = new ProgressDialog(getActivity());
                mprocessingdialog.setTitle("Please Wait..");
                mprocessingdialog.setMessage("Loading");
                mprocessingdialog.setIndeterminate(false);
                mprocessingdialog.show();
            }

            @Override
            protected Void doInBackground(Void... arg0) {
                // TODO Auto-generated method stub
                listDataHeader = new ArrayList<String>();
                JSONParser jp = new JSONParser();
                String jsonstr = jp.makeServiceCall(url, JSONParser.GET);
                Log.d("Json url view", jsonstr);

                if (jsonstr != null) {

                    listDataHeader = new ArrayList<String>();
                    listDataChild = new HashMap<String, List<String>>();

                    try {
                        JSONObject jobj = new JSONObject(jsonstr);
                        JSONArray jarray = jobj.getJSONArray("worldpopulation");
                        for (int hk = 0; hk < jarray.length(); hk++) {
                            JSONObject d = jarray.getJSONObject(hk);
                            // Adding Header data

                            listDataHeader.add(d.getString("country"));
                            // Adding child data for lease offer
                            List<String> lease_offer = new ArrayList<String>();

                            lease_offer.add(d.getString("country") + "'s Rank is : "
                                    + d.getString("rank"));
                            lease_offer.add("And Population is "+d.getString("population"));
                            // Header into Child data
                            listDataChild.put(listDataHeader.get(hk), lease_offer);

                        }
                    } catch (JSONException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }

                } else {
                    Toast.makeText(getActivity(),
                            "Please Check internet Connection", Toast.LENGTH_SHORT)
                            .show();

                }

                return null;
            }

            @Override
            protected void onPostExecute(Void result) {
                // TODO Auto-generated method stub
                super.onPostExecute(result);
                mprocessingdialog.dismiss();

                expandableListAdapter = new info.tranetech.adurec.fragments.Expandable_adapter(
                        getActivity(), listDataHeader, listDataChild);
                Log.i("groups", listDataHeader.toString());
                Log.i("details", listDataChild.toString());
                exp_leaseoffer.setAdapter(expandableListAdapter);

                exp_leaseoffer.setOnGroupClickListener(new OnGroupClickListener() {

                    @Override
                    public boolean onGroupClick(ExpandableListView parent, View v,
                            int groupPosition, long id) {
                        // TODO Auto-generated method stub
                        return false;
                    }

                });
                // Listview Group expanded listener
                exp_leaseoffer
                        .setOnGroupExpandListener(new OnGroupExpandListener() {

                            @Override
                            public void onGroupExpand(int groupPosition) {
                                // Toast.makeText(getActivity().getApplicationContext(),
                                // listDataHeader.get(groupPosition) + " Expanded",
                                // Toast.LENGTH_SHORT).show();
                            }
                        });
                exp_leaseoffer
                        .setOnGroupCollapseListener(new OnGroupCollapseListener() {

                            @Override
                            public void onGroupCollapse(int groupPosition) {
                                Toast.makeText(
                                        getActivity().getApplicationContext(),
                                        listDataHeader.get(groupPosition)
                                                + " Collapsed", Toast.LENGTH_SHORT)
                                        .show();
                            }
                        });
                exp_leaseoffer.setOnChildClickListener(new OnChildClickListener() {

                    @Override
                    public boolean onChildClick(ExpandableListView parent, View v,
                            int groupPosition, int childPosition, long id) {
                        // Toast.makeText(
                        // getActivity().getApplicationContext(),
                        // listDataHeader.get(groupPosition)
                        // + " : "
                        // + listDataChild.get(
                        // listDataHeader.get(groupPosition)).get(
                        // childPosition), Toast.LENGTH_SHORT)
                        // .show();

    //                  Intent ilk = new Intent(getActivity(),
    //                          Lease_Offer_one.class);
    //                  startActivity(ilk);

                        return false;
                    }
                });

            }
        }

        // public Boolean isWifiAvailable() {
        //
        // try {
        // ConnectivityManager connectivityManager = (ConnectivityManager)
        // getActivity()
        // .getSystemService(Context.CONNECTIVITY_SERVICE);
        // NetworkInfo wifiInfo = connectivityManager
        // .getNetworkInfo(ConnectivityManager.TYPE_WIFI);
        //
        // if (wifiInfo.isConnected()) {
        // return true;
        // }
        // } catch (Exception e) {
        // e.printStackTrace();
        // }
        // return false;
        // }

        // public boolean isNetworkAvailable() {
        // ConnectivityManager connectivityManager = (ConnectivityManager)
        // getActivity()
        // .getSystemService(Context.CONNECTIVITY_SERVICE);
        // NetworkInfo activeNetworkInfo = connectivityManager
        // .getActiveNetworkInfo();
        // return activeNetworkInfo != null && activeNetworkInfo.isConnected();
        // }

    }

    **This is Expandable_adapter java class**




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

    import android.content.Context;
    import android.graphics.Typeface;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.BaseExpandableListAdapter;
    import android.widget.TextView;

    public class Expandable_adapter extends BaseExpandableListAdapter {

        private Context _context;
        private List<String> _listDataHeader;
        private HashMap<String, List<String>> _listDataChild;

        public Expandable_adapter(Context context, List<String> listDataHeader,
                HashMap<String, List<String>> listDataChild) {
            this._context = context;
            this._listDataHeader = listDataHeader;
            this._listDataChild = listDataChild;
        }

        @Override
        public Object getChild(int groupPosition, int childPosition) {
            return this._listDataChild.get(this._listDataHeader.get(groupPosition))
                    .get(childPosition);
        }

        @Override
        public long getChildId(int groupPosition, int childPosition) {
            return childPosition;
        }

        @Override
        public View getChildView(int groupPosition, final int childPosition,
                boolean isLastChild, View convertView, ViewGroup parent) {
            final String childText = (String) getChild(groupPosition, childPosition);
            if (convertView == null) {
                LayoutInflater layoutInflater = (LayoutInflater) this._context
                        .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                convertView = layoutInflater.inflate(R.layout.list_child, null);
            }
            TextView expandedListTextView = (TextView) convertView
                    .findViewById(R.id.tv_listchild);
            expandedListTextView.setText(childText);
            return convertView;
        }

        @Override
        public int getChildrenCount(int groupPosition) {
            return this._listDataChild.get(this._listDataHeader.get(groupPosition))
                    .size();
        }

        @Override
        public Object getGroup(int groupPosition) {
            return this._listDataHeader.get(groupPosition);
        }

        @Override
        public int getGroupCount() {
            return this._listDataHeader.size();
        }

        @Override
        public long getGroupId(int groupPosition) {
            return groupPosition;
        }

        @Override
        public View getGroupView(int groupPosition, boolean isExpanded,
                View convertView, ViewGroup parent) {
            String headerTitle = (String) getGroup(groupPosition);
            if (convertView == null) {
                LayoutInflater layoutInflater = (LayoutInflater) this._context
                        .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                convertView = layoutInflater.inflate(R.layout.list_group, null);
            }
            TextView listTitle = (TextView) convertView
                    .findViewById(R.id.tv_listtitle);
            listTitle.setTypeface(null, Typeface.BOLD);
            listTitle.setText(headerTitle);
            return convertView;
        }

        @Override
        public boolean hasStableIds() {
            return false;
        }

        @Override
        public boolean isChildSelectable(int groupPosition, int childPosition) {
            return true;
        }
    }
**xml wellcome_page**
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:background="@drawable/background_welcome" >

    <LinearLayout
        android:id="@+id/header"
        android:layout_width="fill_parent"
        android:layout_height="40dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:background="@drawable/bottom_bar"
        android:orientation="horizontal" >
    </LinearLayout>

    <TextView
        android:id="@+id/tv_welcomeuser"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="8dp"
        android:gravity="center"
        android:text="WELCOME USER"
        android:textColor="#FFFFFF"
        android:textSize="16sp"
        tools:ignore="HardcodedText" />

    <LinearLayout
        android:id="@+id/eeeee"
        android:layout_width="200dp"
        android:layout_height="30dp"
        android:layout_below="@+id/tv_welcomeuser"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="20dp"
        android:background="@drawable/edit_text"
        android:gravity="center" >

        <TextView
            android:id="@+id/tv_recentupdate"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:paddingLeft="20dp"
            android:paddingRight="20dp"
            android:singleLine="true"
            android:text="RECENT UPDATES"
            android:textColor="#FFFFFF"
            android:textSize="18sp"
            tools:ignore="HardcodedText" />

    </LinearLayout>

    <RelativeLayout
        android:id="@+id/expl"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/header"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/eeeee"
        android:layout_marginTop="20dp" >

        <LinearLayout
            android:id="@+id/textLin"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:gravity="center"
            android:orientation="vertical"
            android:weightSum="4" >

            <TextView
                android:id="@+id/tv_adurec"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@+id/lvExp"
                android:layout_centerHorizontal="true"
                android:layout_weight="1"
                android:fontFamily="times_roman"
                android:text="   Powered by "
                android:textColor="#ffffff"
                android:textSize="15dp"
                tools:ignore="ObsoleteLayoutParam,HardcodedText,SpUsage" />

            <TextView
                android:id="@+id/textView1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignRight="@+id/tv_adurec"
                android:layout_centerVertical="true"
                android:layout_marginBottom="10dp"
                android:layout_weight="1"
                android:text="ADUREC"
                android:textAppearance="?android:attr/textAppearanceMedium"
                android:textColor="#ffffff"
                tools:ignore="ObsoleteLayoutParam,HardcodedText" />

        </LinearLayout>

        <ExpandableListView
            android:id="@+id/lvExp"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_above="@+id/textLin"
            android:listSelector="@drawable/buttons_effacts"
            android:divider="@color/list_divider"
            android:dividerHeight="0.8dip"
            android:layout_alignParentLeft="true"
            android:layout_alignParentTop="true" >
        </ExpandableListView>
    </RelativeLayout>

</RelativeLayout>

**list_child.xml **
<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center">
    <TextView
        android:id="@+id/tv_listchild"
        android:layout_width="fill_parent"
        android:layout_height="40dp"
        android:paddingTop="10dp"
        android:textSize="16sp"
        android:gravity="center"
        android:textColor="#7D1023"
        android:background="#ffffff"
        android:paddingBottom="10dp" />
</LinearLayout>

**list_group.xml**
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/tv_listtitle"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:background="@drawable/buttons_effacts"
        android:padding="15dp"
        android:gravity="center"
        android:paddingLeft="?android:attr/expandableListPreferredItemPaddingLeft"
        android:textColor="#ffffff"
        android:textSize="16sp" />

</LinearLayout>