JSON Parsing

// AlbumsActivity.java
package com.example.jsonapp;

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

import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;

import com.example.helper.AlertDialogManager;
import com.example.helper.ConnectionDetector;
import com.example.helper.JSONParser;

public class AlbumsActivity extends ListActivity {
    // Connection detector
    ConnectionDetector cd;

    // Alert dialog manager
    AlertDialogManager alert = new AlertDialogManager();

    // Progress Dialog
    private ProgressDialog pDialog;

    // Creating JSON Parser object
    JSONParser jsonParser = new JSONParser();

    ArrayList<HashMap<String, String>> albumsList;

    // albums JSONArray
    JSONArray albums = null;

    // albums JSON url
    private static final String URL_ALBUMS = "http://api.androidhive.info/songs/albums.php";

    // ALL JSON node names
    private static final String TAG_ID = "id";
    private static final String TAG_NAME = "name";
    private static final String TAG_SONGS_COUNT = "songs_count";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_albums);

        cd = new ConnectionDetector(getApplicationContext());

        // Check for internet connection
        if (!cd.isConnectingToInternet()) {
            // Internet Connection is not present
            alert.showAlertDialog(AlbumsActivity.this, "Internet Connection Error",
                    "Please connect to working Internet connection", false);
            // stop executing code by return
            return;
        }

        // Hashmap for ListView
        albumsList = new ArrayList<HashMap<String, String>>();

        // Loading Albums JSON in Background Thread
        new LoadAlbums().execute();

        // get listview
        ListView lv = getListView();

        /**
         * Listview item click listener
         * TrackListActivity will be lauched by passing album id
         * */
        lv.setOnItemClickListener(new android.widget.AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> arg0, View view, int arg2,
                    long arg3) {
                // on selecting a single album
                // TrackListActivity will be launched to show tracks inside the album
                Intent i = new Intent(getApplicationContext(), TrackListActivity.class);

                // send album id to tracklist activity to get list of songs under that album
                String album_id = ((TextView) view.findViewById(R.id.album_id)).getText().toString();
                i.putExtra("album_id", album_id);

                startActivity(i);
            }
        });
    }

    /**
     * Background Async Task to Load all Albums by making http request
     * */
    class LoadAlbums extends AsyncTask<String, String, String> {

        /**
         * Before starting background thread Show Progress Dialog
         * */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(AlbumsActivity.this);
            pDialog.setMessage("Listing Albums ...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();
        }

        /**
         * getting Albums JSON
         * */
        protected String doInBackground(String... args) {
            // Building Parameters
            List<NameValuePair> params = new ArrayList<NameValuePair>();

            // getting JSON string from URL
            String json = jsonParser.makeHttpRequest(URL_ALBUMS, "GET",
                    params);

            // Check your log cat for JSON reponse
            Log.d("Albums JSON: ", "> " + json);

            try {
                albums = new JSONArray(json);

                if (albums != null) {
                    // looping through All albums
                    for (int i = 0; i < albums.length(); i++) {
                        JSONObject c = albums.getJSONObject(i);

                        // Storing each json item values in variable
                        String id = c.getString(TAG_ID);
                        String name = c.getString(TAG_NAME);
                        String songs_count = c.getString(TAG_SONGS_COUNT);

                        // creating new HashMap
                        HashMap<String, String> map = new HashMap<String, String>();

                        // adding each child node to HashMap key => value
                        map.put(TAG_ID, id);
                        map.put(TAG_NAME, name);
                        map.put(TAG_SONGS_COUNT, songs_count);

                        // adding HashList to ArrayList
                        albumsList.add(map);
                    }
                }else{
                    Log.d("Albums: ", "null");
                }

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

            return null;
        }

        /**
         * After completing background task Dismiss the progress dialog
         * **/
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after getting all albums
            pDialog.dismiss();
            // updating UI from Background Thread
            runOnUiThread(new Runnable() {
                public void run() {
                    /**
                     * Updating parsed JSON data into ListView
                     * */
                    ListAdapter adapter = new SimpleAdapter(
                            AlbumsActivity.this, albumsList,
                            R.layout.list_item_albums, new String[] { TAG_ID,
                                    TAG_NAME, TAG_SONGS_COUNT }, new int[] {
                                    R.id.album_id, R.id.album_name, R.id.songs_count });

                    // updating listview
                    setListAdapter(adapter);
                }
            });

        }

    }
}

//activity_albums.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:background="#ffffff">

    <ListView
        android:id="@+id/list"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:divider="#b5b5b5"
        android:dividerHeight="1dp"
        android:cacheColorHint="#00000000" >
    </ListView>

</LinearLayout>

//activity_tracks.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:background="#ffffff">

    <ListView
        android:id="@android:id/list"
        ></ListView>


</LinearLayout>


//list_item_albums.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/RelativeLayout1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/album_id"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:visibility="gone" />

    <TextView
        android:id="@+id/album_name"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textSize="16dip"
        android:textColor="#000000"
        android:paddingTop="15dip"
        android:paddingBottom="15dip"
        android:paddingLeft="10dip"
        android:textStyle="bold"/>

    <TextView
        android:id="@+id/songs_count"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:textColor="#ffffff"
        android:textStyle="bold"
        android:background="#9ed321"
        android:paddingRight="3dip"
        android:paddingLeft="3dip" />

</RelativeLayout>



//log

12-29 11:32:13.611: W/Trace(1507): Unexpected value from nativeGetEnabledTags: 0
12-29 11:32:13.649: W/Trace(1507): Unexpected value from nativeGetEnabledTags: 0
12-29 11:32:14.309: D/dalvikvm(1507): GC_FOR_ALLOC freed 62K, 7% free 2571K/2752K, paused 47ms, total 50ms
12-29 11:32:14.319: I/dalvikvm-heap(1507): Grow heap (frag case) to 3.229MB for 635812-byte allocation
12-29 11:32:14.449: D/dalvikvm(1507): GC_FOR_ALLOC freed 1K, 6% free 3190K/3376K, paused 122ms, total 122ms
12-29 11:32:14.589: D/dalvikvm(1507): GC_CONCURRENT freed <1K, 6% free 3202K/3376K, paused 5ms+73ms, total 146ms
12-29 11:32:14.609: D/AndroidRuntime(1507): Shutting down VM
12-29 11:32:14.609: W/dalvikvm(1507): threadid=1: thread exiting with uncaught exception (group=0x40a70930)
12-29 11:32:14.629: E/AndroidRuntime(1507): FATAL EXCEPTION: main
12-29 11:32:14.629: E/AndroidRuntime(1507): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.jsonapp/com.example.jsonapp.AlbumsActivity}: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list'
12-29 11:32:14.629: E/AndroidRuntime(1507):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at android.os.Handler.dispatchMessage(Handler.java:99)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at android.os.Looper.loop(Looper.java:137)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at android.app.ActivityThread.main(ActivityThread.java:5039)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at java.lang.reflect.Method.invokeNative(Native Method)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at java.lang.reflect.Method.invoke(Method.java:511)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at dalvik.system.NativeStart.main(Native Method)
12-29 11:32:14.629: E/AndroidRuntime(1507): Caused by: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list'
12-29 11:32:14.629: E/AndroidRuntime(1507):     at android.app.ListActivity.onContentChanged(ListActivity.java:243)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:273)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at android.app.Activity.setContentView(Activity.java:1881)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at com.example.jsonapp.AlbumsActivity.onCreate(AlbumsActivity.java:58)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at android.app.Activity.performCreate(Activity.java:5104)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
12-29 11:32:14.629: E/AndroidRuntime(1507):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
12-29 11:32:14.629: E/AndroidRuntime(1507):     ... 11 more
12-29 11:32:28.329: I/Process(1507): Sending signal. PID: 1507 SIG: 9