android - русском - firebase.js что это




Задать список из JSON (4)

Кто-нибудь знает какие-либо примеры для динамической загрузки данных Json в ListView, большинство примеров, которые я видел, просто используют статический массив какого-то типа. Мне нужно загрузить, например, 10 строк данных Json, а затем внизу загрузить больше .., чтобы получить следующие 10 и т. Д. Примеры с использованием Json пожалуйста ....


Android не имеет готового адаптера для заполнения ListView массивом JSON, как и для заполнения ListView с записями базы данных.

Я рекомендую вам успеть с заполнением структуры данных Java по вашему выбору данными JSON и удобством работы с ListViews , ListViews их из разных коллекций и различными пользовательскими строками.

Вот простой пример заполнения List из массива JSON, а затем с помощью List для заполнения ListView .

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

import org.json.JSONArray;

import android.app.Activity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class Main extends Activity
{
  @Override
  public void onCreate(Bundle savedInstanceState)
  {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    try
    {
      String jsonInput = "[\"one\",\"two\",\"three\",\"four\",\"five\",\"six\",\"seven\",\"eight\",\"nine\",\"ten\"]";
      JSONArray jsonArray = new JSONArray(jsonInput);
      int length = jsonArray.length();
      List<String> listContents = new ArrayList<String>(length);
      for (int i = 0; i < length; i++)
      {
        listContents.add(jsonArray.getString(i));
      }

      ListView myListView = (ListView) findViewById(R.id.my_list);
      myListView.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, listContents));
    }
    catch (Exception e)
    {
      // this is just an example
    }
  }
}

Попробуйте следующее:

Класс JSON Parser:

public class JSONParser {

    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";

    // constructor
    public JSONParser() {

    }

    // function get json from url
    // by making HTTP POST or GET mehtod
    public JSONObject makeHttpRequest(String url, String method,
            List<NameValuePair> params) {

        // Making HTTP request
        try {

            // check for request method
            if (method == "POST") {
                // request method is POST
                // defaultHttpClient
                DefaultHttpClient httpClient = new DefaultHttpClient();
                HttpPost httpPost = new HttpPost(url);
                httpPost.setEntity(new UrlEncodedFormEntity(params));

                HttpResponse httpResponse = httpClient.execute(httpPost);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();

            } else if (method == "GET") {
                // request method is GET
                DefaultHttpClient httpClient = new DefaultHttpClient();
                String paramString = URLEncodedUtils.format(params, "utf-8");
                url += "?" + paramString;
                HttpGet httpGet = new HttpGet(url);

                HttpResponse httpResponse = httpClient.execute(httpGet);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();
            }

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            json = sb.toString();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

        // try parse the string to a JSON object
        try {
            jObj = new JSONObject(json);
        } catch (JSONException e) {
            Log.e("JSON Parser", "Error parsing data " + e.toString());
        }

        // return JSON String
        return jObj;

    }
}

Класс фрагмента, показывающий Listview:

public static class EventFragment extends ListFragment {

        ArrayList<HashMap<String, String>> eventsList;
        private String url_all_events = //url goes here;
        private ProgressDialog pDialog;

        JSONParser jParser = new JSONParser();

        // JSON Node names
        private static final String CONNECTION_STATUS = "success";
        private static final String TABLE_EVENT = "Event";
        private static final String pid = "pid";
        private static final String COL_GROUP = "Group";
        private static final String COL_NAME = "Event_Name";
        private static final String COL_DESC = "Event_Desc";
        private static final String COL_DATE = "Event_Date";
        private static final String COL_TIME = "Event_Time";

        JSONArray Events = null;

        public static final String ARG_SECTION_NUMBER = "section_number";

        public EventFragment() {
        }

        public void onStart() {
            super.onStart();

            eventsList = new ArrayList<HashMap<String, String>>();
            new LoadAllEvents().execute();

            // selecting single ListView item
            ListView lv = getListView();

            // Lauching the Event details screen on selecting a single event
            lv.setOnItemClickListener(new OnItemClickListener() {

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

                    Intent intent = new Intent(view.getContext(),
                            EventDetails.class);
                    intent.putExtra(pid, ID);
                    view.getContext().startActivity(intent);
                }
            });
        }

        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_events,
                    container, false);

            return rootView;
        }

        class LoadAllEvents extends AsyncTask<String, String, String> {

            /**
             * Before starting background thread Show Progress Dialog
             * */
            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                pDialog = new ProgressDialog(getActivity());
                pDialog.setMessage("Just a moment...");
                pDialog.setIndeterminate(true);
                pDialog.setCancelable(true);
                pDialog.show();
            }

            protected String doInBackground(String... args) {
                // Building Parameters
                List<NameValuePair> params = new ArrayList<NameValuePair>();
                // getting JSON string from URL
                JSONObject json = jParser.makeHttpRequest(url_all_events,
                        "GET", params);

                try {
                    // Checking for SUCCESS TAG
                    int success = json.getInt(CONNECTION_STATUS);

                    if (success == 1) {
                        // products found
                        // Getting Array of Products
                        Events = json.getJSONArray(TABLE_EVENT);
                        // looping through All Contacts
                        for (int i = 0; i < Events.length(); i++) {
                            JSONObject evt = Events.getJSONObject(i);

                            // Storing each json item in variable
                            id = evt.getString(pid);
                            group = evt.getString(COL_GROUP);
                            name = evt.getString(COL_NAME);
                            desc = evt.getString(COL_DESC);
                            date = evt.getString(COL_DATE);
                            time = evt.getString(COL_TIME);

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

                            // adding each child node to HashMap key => value
                            map.put(pid, id);
                            map.put(COL_GROUP, group);
                            map.put(COL_NAME, name);
                            map.put(COL_DESC, desc);
                            map.put(COL_DATE, date);
                            map.put(COL_TIME, time);

                            // adding HashList to ArrayList
                            eventsList.add(map);
                        }
                    } else {
                        // Options are not available or server is down.
                        // Dismiss the loading dialog and display an alert
                        // onPostExecute
                        pDialog.dismiss();
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }

                return null;
            }

            protected void onPostExecute(String file_url) {
                // dismiss the dialog after getting all products
                pDialog.dismiss();
                // updating UI from Background Thread
                getActivity().runOnUiThread(new Runnable() {
                    public void run() {
                        ListAdapter adapter = new SimpleAdapter(getActivity(),
                                eventsList, R.layout.list_item, new String[] {
                                        pid, COL_GROUP, COL_NAME, COL_DATE, COL_TIME },
                                new int[] { R.id.pid, R.id.group, R.id.name, R.id.header,
                                        R.id.title2 });

                        setListAdapter(adapter);
                    }
                });

            }

        }
    }

Информация о деятельности класс:

public class EventDetails extends Activity {

    String pid;
    TextView EvtName, EvtDesc, EvtDate, EvtTime, Header;
    ImageView logo;

    private String url_event_details = "http://centrubook.eu.pn/eventDetails.php";
    private ProgressDialog pDialog;

    JSONParser jParser = new JSONParser();

    // JSON Node names
    private static final String CONNECTION_STATUS = "success";
    private static final String TABLE_EVENT = "Event";
    private static final String COL_PID = "pid";
    private static final String COL_NAME = "Event_Name";
    private static final String COL_DESC = "Event_Desc";
    private static final String COL_DATE = "Event_Date";
    private static final String COL_TIME = "Event_Time";

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
        // Respond to the action bar's Up/Home button
        case android.R.id.home:
            NavUtils.navigateUpFromSameTask(this);
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

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

        // ActionBar actionBar = getActionBar();
        // actionBar.setDisplayHomeAsUpEnabled(true);

        EvtName = (TextView) findViewById(R.id.BombaName);
        EvtDesc = (TextView) findViewById(R.id.BombaDesc);
        EvtDate = (TextView) findViewById(R.id.BombaDate);
        EvtTime = (TextView) findViewById(R.id.BombaTime);
        logo = (ImageView) findViewById(R.id.BombaLogo);

        Intent i = getIntent();
        pid = i.getStringExtra(COL_PID);
        new getEventDetails().execute();
    }

    class getEventDetails extends AsyncTask<String, String, String> {

        String name, desc, date, time;

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(EventDetails.this);
            pDialog.setMessage("Just a moment...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(true);
            pDialog.show();
        }

        @Override
        protected String doInBackground(String... args) {

            // Check for success tag
            int success;
            try {
                List<NameValuePair> params = new ArrayList<NameValuePair>();
                params.add(new BasicNameValuePair("pid", pid));

                // getting product details by making HTTP request
                // Note that product details url will use GET request
                JSONObject json = jParser.makeHttpRequest(url_event_details,
                        "GET", params);

                // json success tag
                success = json.getInt(CONNECTION_STATUS);
                if (success == 1) {
                    // successfully received product details
                    JSONArray eventsObj = json.getJSONArray(TABLE_EVENT);

                    // get first product object from JSON Array
                    JSONObject details = eventsObj.getJSONObject(0);

                    name = details.getString(COL_NAME);
                    desc = details.getString(COL_DESC);
                    date = details.getString(COL_DATE);
                    time = details.getString(COL_TIME);

                } else {
                    // product with pid not found
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
            return null;
        }

        protected void onPostExecute(final String file_url) {
            pDialog.dismiss();

            runOnUiThread(new Runnable() {
                public void run() {

                    EvtName.setText(name);
                    EvtDesc.setText(desc);
                    EvtDate.setText(date);
                    EvtTime.setText(time);
                    logo.setImageResource(R.drawable.events);

                }
            });
        }
    }
}

Надеюсь это поможет ;)


У dbaugh есть хороший ответ, но this пост объясняет, как использовать его для всех нас, кто не знает, куда идти оттуда.


Я сделал простой JSONAdapter следующим образом:

public abstract class JSONAdapter extends BaseAdapter {

private JSONArray array;

@Override
public int getCount() {
    return array == null ? 0 : array.length();
}

@Override
public Object getItem(final int position) {
    if (array == null | array.length() < position) {
        return null;
    }
    try {
        return array.get(position);
    } catch (final JSONException e) {
        e.printStackTrace();
        return null;
    }
}

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

public JSONObject getObject(final int position) {
    return (JSONObject) getItem(position);
}

public void setData(final JSONArray data) {
    array = data;
    notifyDataSetChanged();
}
}

а затем, когда мне нужен конкретный экземпляр, я должен переопределить метод getView в адаптере с моей конкретной потребностью:

@Override
public View getView(final int position, final View convertView,
        final ViewGroup parent) {
    final View view;
    final ViewHolder holder;
    if (convertView != null) {
        view = convertView;
        holder = (ViewHolder) view.getTag();
    } else {
        view = context.getLayoutInflater().inflate(
                R.layout.<mylayout>, parent, false);
        holder = new ViewHolder();
        holder.name = (TextView) view.findViewById(R.id.name);
                    [...]
        view.setTag(holder);
    }
    final JSONObject jsonObj = getObject(position);
    holder.name.setText(jsonObj.optString("name"));
    [...]
    return view;
}

и установите данные следующим образом:

final JSONObject json = new JSONObject(jsonString);
adapter.setData(json.getJSONArray("projects"));




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