Cannot cast from FragmentActivity to ListFragment

Question 1

java.lang.IllegalStateException:Content view not yet created

Move the code in onCreate to onActivityCreated. Override onActivityCreated.

Edit:

public class WorkersFragment extends Fragment {

    private ProgressDialog pDialog;

    // URL to get contacts JSON
    private static String url = "http://teamdoge.com/index.php?page=api&action=getdashboarddata&api_key=5a0a4793431873828540ae6ddad556075b169180d5b16023a41daec8530b890f&id=2317";

    // JSON Node names
    private static final String TAG_DASHDATA = "getdashboarddata";
    private static final String TAG_DATA = "data";
    private static final String TAG_PERSONAL = "personal";
    private static final String TAG_WORKERS = "workers";
    private static final String TAG_ID = "id";
    private static final String TAG_USERNAME = "username";
    private static final String TAG_HASHRATE = "hashrate";
    private static final String TAG_PHONE_MOBILE = "mobile";
    private static final String TAG_PHONE_HOME = "home";
    private static final String TAG_PHONE_OFFICE = "office";
    JSONArray workers = null;
    ListView lv;
    ArrayList<HashMap<String, String>> contactList;

    public static WorkersFragment newInstance(String text) {
        WorkersFragment pageFragment = new WorkersFragment();

        return pageFragment;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)   {
        View view = inflater.inflate(R.layout.worker_fragment, container, false);

        return view;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onActivityCreated(savedInstanceState);
        lv = (ListView) getView().findViewById(R.id.listView1); 
        contactList = new ArrayList<HashMap<String, String>>();

        pDialog = new ProgressDialog(getActivity());
        pDialog.setMessage("Please wait...");
        pDialog.setCancelable(false);

        lv.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                // getting values from selected ListItem
                String name = ((TextView) view.findViewById(R.id.textView1))
                        .getText().toString();
                String cost = ((TextView) view.findViewById(R.id.textView2))
                        .getText().toString();
                String description = ((TextView) view.findViewById(R.id.textView3))
                        .getText().toString();

                // Starting single contact activity
//                Intent in = new Intent(getActivity().getApplicationContext(),SingleContactActivity.class);
//                in.putExtra(TAG_ID, name);
//                in.putExtra(TAG_USERNAME, cost);
//                in.putExtra(TAG_HASHRATE, description);
//                startActivity(in);

            }
        });

        // Calling async task to get json
        new GetContacts().execute();
    }



    /**
     * Async task class to get json by making HTTP call
     * */
    private class GetContacts extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            // Showing progress dialog

            pDialog.show();

        }

        @Override
        protected Void doInBackground(Void... arg0) {

            try
           {
            HttpClient httpclient = new DefaultHttpClient();
            httpclient.getParams().setParameter(CoreProtocolPNames.PROTOCOL_VERSION, HttpVersion.HTTP_1_1);
            HttpGet request = new HttpGet(url);
            // HttpGet request = new HttpGet("http://gdata.youtube.com/feeds/api/users/mbbangalore/uploads?v=2&alt=jsonc");     

            HttpResponse response = httpclient.execute(request);
            HttpEntity resEntity = response.getEntity();
            String _response=EntityUtils.toString(resEntity);
            if (_response!= null) {

                    //JSONObject jsonObj2 = new JSONObject(jsonStr);

                    // Get the root JSONObject
                    JSONObject jsonObject = new JSONObject(_response);

                    // Get the JSON object named query
                    //JSONObject getpoolstatusJSONObject = jsonObject.getJSONObject("getpoolstatus");
                    JSONObject getpoolstatusJSONObject = jsonObject.getJSONObject("getdashboarddata");

                    // Get the JSON object named results inside of the query object
                    //JSONObject dataJSONObject = getpoolstatusJSONObject.getJSONObject("data");
                    JSONObject dataJSONObject = getpoolstatusJSONObject.getJSONObject("data");

                    // Get the JSON object named quote inside of the results object
                    JSONObject personalJSONObject = dataJSONObject.getJSONObject("personal");
                   workers = personalJSONObject.getJSONArray(TAG_WORKERS);


                    for (int i = 0; i < workers.length(); i++) {
                        JSONObject c = workers.getJSONObject(i);

                        String id = c.getString(TAG_ID);
                        String name = c.getString(TAG_USERNAME);
                        String email = c.getString(TAG_HASHRATE);
                        HashMap<String, String> contact = new HashMap<String, String>();

                        // adding each child node to HashMap key => value
                        contact.put(TAG_ID, "ID: " + id);
                        contact.put(TAG_USERNAME, name);
                        contact.put(TAG_HASHRATE, email + " kH/s");

                        contactList.add(contact); 
                 }
             }
             }
            catch(Exception e)
            {
                e.printStackTrace();
            }

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);
            // Dismiss the progress dialog
            if (pDialog.isShowing())
                pDialog.dismiss();
            ListAdapter adapter = new SimpleAdapter(
                    getActivity(), contactList,
                    R.layout.list_item, new String[] { TAG_ID, TAG_USERNAME,
                            TAG_HASHRATE }, new int[] { R.id.textView1,
                            R.id.textView2, R.id.textView3});

            lv.setAdapter(adapter);
        }

    }
}

list_item.xml

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

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="33dp"
        android:layout_marginTop="40dp"
        android:text="TextView" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/textView1"
        android:layout_centerHorizontal="true"
        android:text="TextView" />

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/textView2"
        android:layout_alignBottom="@+id/textView2"
        android:layout_alignParentRight="true"
        android:layout_marginRight="26dp"
        android:text="TextView" />

</RelativeLayout>

wokers_fragment.xml

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

    <ListView
        android:id="@+id/listView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" >

    </ListView>

</RelativeLayout>

Snap

enter image description here

Question 2

You can't cast the Activity to a Fragment; they are completely different, and you are already inside the Fragment instance.

You can't call the getList() method from onCreate(), because the Views aren't initialized at this point; you should move that logic to onViewCreated() instead.

Question 3

You can't do this: ((ListFragment) getActivity()).getListView();

The ListView you're looking for is in the ListFragment you are hosting in that Activity.

Time to go back to school…

Please review the documentation for a ListFragment, an Activity and how to communicate between Fragments (and Activities).

The answer is there and it will help you understand the problem.