Remplir la liste depuis JSON
Est-ce que quelqu'un connaît des exemples pour charger dynamiquement Jsondata dans un ListView, la plupart des exemples que j'ai vus ne font qu'utiliser un tableau statique D'une certaine sorte. J'ai besoin de charger disons 10 lignes de données Json, puis, au bas, une charge supplémentaire .. pour obtenir le next 10 etc etc. Des exemples utilisant Json s'il vous plaît ....
Le programmeur Bruce a raison, il n’ya pas de moyen par défaut de le faire. Cependant, il existe un moyen très simple et très propre d’y parvenir. Voici l'adaptateur que j'utilise pour gérer JSONArrays.
class JSONAdapter extends BaseAdapter implements ListAdapter {
private final Activity activity;
private final JSONArray jsonArray;
private JSONAdapter(Activity activity, JSONArray jsonArray) {
assert activity != null;
assert jsonArray != null;
this.jsonArray = jsonArray;
this.activity = activity;
}
@Override public int getCount() {
return jsonArray.length();
}
@Override public JSONObject getItem(int position) {
return jsonArray.optJSONObject(position);
}
@Override public long getItemId(int position) {
JSONObject jsonObject = getItem(position);
return jsonObject.optLong("id");
}
@Override public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null)
convertView = activity.getLayoutInflater().inflate(R.layout.row, null);
JSONObject jsonObject = getItem(position);
return convertView;
}
}
Android ne dispose pas d'un adaptateur prêt à l'emploi pour renseigner une ListView avec un tableau JSON, comme pour le remplissage d'une ListView avec des enregistrements de base de données.
Je vous recommande de vous familiariser avec le remplissage d'une structure de données Java de votre choix avec les données JSON et de pouvoir utiliser ListViews, en les renseignant à partir de différentes collections, avec différentes lignes personnalisées.
Voici un exemple simple de remplissage d'une List à partir d'un tableau JSON, puis d'utilisation de la variable List pour remplir une 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
}
}
}
Essayez le ci-dessous:
Classe d'analyse JSON:
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;
}
}
Fragment class montrant 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);
}
});
}
}
}
Classe de détails de l'activité:
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);
}
});
}
}
}
J'espère que cela t'aides ;)
dbaugh a une bonne réponse, mais this post explique comment l’utiliser pour le reste de nous qui ne savons pas où aller à partir de là.
J'ai fait un simple JSONAdapter comme ceci:
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();
}
}
et puis quand j'ai besoin d'une instance spécifique de celle-ci, je dois remplacer la méthode getView dans l'adaptateur par mon besoin concret:
@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;
}
et définissez les données comme ceci:
final JSONObject json = new JSONObject(jsonString);
adapter.setData(json.getJSONArray("projects"));