Develop Reference

Android - Display data from Adapter in Listview

I've currently got an application that pulls data from a mysql database and displays it in raw JSON format. I'm currently working on pushing this data into a String variable and displaying it on a Listview on a specific activity.
Problem is, when trying to display this data, my Listview is not populating; I'm sure the variable is not empty as the if statement would have captured this.
Here is snippet of MainActivity code:
//Methods to grab information from abhandym_DB database
public void getJSON(View view){
new BackgroundTask().execute();
}
public void parseJSON(View view){
if(JSON_String==null){
Toast.makeText(getApplicationContext(), "First Get Json", Toast.LENGTH_LONG).show();
}else{
Intent intent = new Intent(this,Test.class);
intent.putExtra("JSON_Data",JSON_String);
startActivity(intent);
}
}
class BackgroundTask extends AsyncTask<Void,Void,String>{
String json_url;
#Override
protected void onPreExecute() {
json_url = "http://abhandyman.x10host.com/json_get_data.php";
}
#Override
protected String doInBackground(Void... params) {
try {
URL url = new URL(json_url);
HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
InputStream inputSteam = httpURLConnection.getInputStream();
BufferedReader buffereredReader = new BufferedReader(new InputStreamReader(inputSteam));
StringBuilder stringBuilder = new StringBuilder();
while((JSON_String = buffereredReader.readLine())!=null){
stringBuilder.append(JSON_String+"\n");
}
buffereredReader.close();
inputSteam.close();
httpURLConnection.disconnect();
return stringBuilder.toString().trim();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
}
#Override
protected void onPostExecute(String result) {
TextView textView = (TextView)findViewById(R.id.fragment1_textview_JSONAPPEAR);
textView.setText(result);
JSON_String = result;
}
}
Here is the code for my Test.java
public class Test extends AppCompatActivity {
String JSON_String;
JSONObject jsonObject;
JSONArray jsonArray;
DataAdapter dataAdapter;
ListView listView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.test_layout);
listView = (ListView)findViewById(R.id.test_listView);
dataAdapter = new DataAdapter(this, R.layout.row_layout);
listView.setAdapter(dataAdapter);
JSON_String = getIntent().getExtras().getString("JSON_Data");
try {
jsonObject = new JSONObject(JSON_String);
jsonArray = jsonObject.getJSONArray("server_response");
int count = 0;
String jobid,problem,resolution;
while(count<jsonObject.length()){
JSONObject JO = jsonArray.getJSONObject(count);
jobid = JO.getString("jobid");
problem = JO.getString("problem");
resolution = JO.getString("resolution");
Data data = new Data(jobid,problem,resolution);
dataAdapter.add(data);
count++;
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
Here is the code for my DataAdapter:
public class DataAdapter extends ArrayAdapter{
List list = new ArrayList();
public DataAdapter(Context context, int resource) {
super(context, resource);
}
public void add(Data object) {
super.add(object);
list.add(object);
}
#Override
public int getCount() {
return list.size();
}
#Override
public Object getItem(int position) {
return list.get(position);
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View row;
row = convertView;
DataHolder dataHolder;
if(row == null){
LayoutInflater layoutInflater = (LayoutInflater)this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = layoutInflater.inflate(R.layout.row_layout,parent,false);
dataHolder = new DataHolder();
dataHolder.tx_jobid = (TextView) row.findViewById(R.id.tx_jobid);
dataHolder.tx_problem = (TextView) row.findViewById(R.id.tx_problem);
dataHolder.tx_resolution = (TextView) row.findViewById(R.id.tx_resolution);
row.setTag(dataHolder);
}else{
dataHolder = (DataHolder)row.getTag();
}
Data data = (Data)this.getItem(position);
dataHolder.tx_jobid.setText(data.getJobid());
dataHolder.tx_problem.setText(data.getProblem());
dataHolder.tx_resolution.setText(data.getResolution());
return row;
}
static class DataHolder{
TextView tx_jobid,tx_problem,tx_resolution;
}
}
and here is what it displays when clicking on "Parse JSON" button.
listView empty after population
Any help or advise on why its not displaying would be much appreciated!
Thanks in advance!

your problem seems to be here :
while(count<jsonObject.length()){
you're not looping using the number of array elements but using the number of mapped key:value object which is one (the "server_response") , you have to change this line to :
while(count<jsonArray.length()){
,
you have just the first element showing because jsonObject.length() will return 1 since it have just one element.
from the doc, JSONObject, length() method:
Returns the number of name/value mappings in this object.
and in your case you have just one name/value mapped ("server_response":[array items...])

Check in Test.java. I think You are setting the adapter to the listview before adding data to it
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.test_layout);
listView = (ListView)findViewById(R.id.test_listView);
dataAdapter = new DataAdapter(this, R.layout.row_layout);
JSON_String = getIntent().getExtras().getString("JSON_Data");
try {
jsonObject = new JSONObject(JSON_String);
jsonArray = jsonObject.getJSONArray("server_response");
int count = 0;
String jobid,problem,resolution;
while(count<jsonObject.length()){
JSONObject JO = jsonArray.getJSONObject(count);
jobid = JO.getString("jobid");
problem = JO.getString("problem");
resolution = JO.getString("resolution");
Data data = new Data(jobid,problem,resolution);
dataAdapter.add(data);
count++;
}
} catch (JSONException e) {
e.printStackTrace();
}
listView.setAdapter(dataAdapter); //change effected
}

Reading JSON array to listview

I'm pretty new to android dev and I need some help.
I'm building an agenda that loads the information from a JSON then a ListView is inflated with a custom adapter. I've done this and works just fine.
My problem is the following when I click a contact another Activity is loaded with more information about the user, using the same JSON. I debug it and it recieves the information like this:
Example Item: [{"id":1,"name":"Leanne Graham","hobby":"Play soccer","address":"Kulas Light, Gwenborough","phone":"1-770-736-8031 x56442"}]
Because I sent the information as a JSONObject I cast it to be a JSONArray, but when I pass that array to my requestComplete my app breaks.
The error is:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
/**Main activity onclick listener*/
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
System.out.println("POSITION: " + position);
JSONObject jsonObject = (JSONObject)JSONadapter.getItem(position);
Intent intent = new Intent(this, InfoActivity.class);
String pos_json = jsonObject.toString();
intent.putExtra("pos_json",pos_json);
startActivity(intent);
}
/**Info activity*/
public class InfoActivity extends AppCompatActivity implements JSONRequest.JSONCallback {
AdapterInfo JSONAdapter;
private ListView listInfo;
private JSONObject json_object;
private JSONArray arrayMain;
private ArrayList<String> jsonarray;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_info);
JSONArray array = new JSONArray();
try {
json_object = new JSONObject(getIntent().getStringExtra("pos_json"));
arrayMain = array.put(json_object);
System.out.println("Example Item: "+ arrayMain.toString());
System.out.println(arrayMain.getClass().getName());
} catch (JSONException e) {
e.printStackTrace();
}
requestComplete(arrayMain);
this.listInfo = (ListView) findViewById(R.id.listView2);
}
#Override
public void requestComplete(JSONArray array) {
JSONAdapter = new AdapterInfo(InfoActivity.this,array);
this.listInfo.setAdapter(JSONAdapter);
}
/**Adapter*/
public class AdapterInfo extends BaseAdapter{
private JSONArray array;
private Activity infoAct;
public AdapterInfo(Activity infoAct, JSONArray array){
this.array = array;
this.infoAct = infoAct;
}
#Override
public int getCount() {
if(array == null){
return 0;
}else{
return array.length();
}
}
#Override
public JSONObject getItem(int position) {
if(array == null){
return null;
}else{
return array.optJSONObject(position);
}
}
#Override
public long getItemId(int position) {
JSONObject object = getItem(position);
return object.optLong("id");
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if(convertView==null){
convertView = infoAct.getLayoutInflater().inflate(R.layout.row,null);
}
TextView name = (TextView)convertView.findViewById(R.id.infoName);
TextView hobby = (TextView)convertView.findViewById(R.id.infoHobby);
TextView address = (TextView)convertView.findViewById(R.id.infoAddress);
TextView phone = (TextView)convertView.findViewById(R.id.infoPhone);
JSONObject json_data = getItem(position);
if(json_data != null){
try {
String nombre = json_data.getString("name");
String pasatiempo = json_data.getString("hobby");
String direccion = json_data.getString("address");
String telefono = json_data.getString("phone");
name.setText(nombre);
hobby.setText(pasatiempo);
address.setText(direccion);
phone.setText(telefono);
} catch (JSONException e) {
e.printStackTrace();
}
}
return convertView;
}}
/**JSONRequest*/
public class JSONRequest extends AsyncTask<String, Void, JSONArray> {
private JSONCallback callback;
public JSONRequest(JSONCallback callback){
this.callback = callback;
}
#Override
protected JSONArray doInBackground(String... params) {
URLConnection connection = null;
BufferedReader br = null;
JSONArray result = null;
try{
URL url = new URL(params[0]);
connection = (URLConnection) url.openConnection();
InputStream is = connection.getInputStream();
br = new BufferedReader(new InputStreamReader(is));
StringBuilder builder = new StringBuilder();
String line = "";
while((line = br.readLine()) != null){
builder.append(line);
}
result = new JSONArray(builder.toString());
}catch (Exception e) {
e.printStackTrace();
} finally {
try{
if(br != null) br.close();
}catch(Exception e) {
e.printStackTrace();
}
}
return result;
}
#Override
protected void onPostExecute(JSONArray jsonArray) {
super.onPostExecute(jsonArray);
callback.requestComplete(jsonArray);
}
public interface JSONCallback{
void requestComplete(JSONArray array);
}}

Your code:
requestComplete(arrayMain);
this.listInfo = (ListView) findViewById(R.id.listView2);
requestComplete() uses this.listInfo instance but this.listInfo is null because it is set after requestComplete(). So you need to switch their order.
this.listInfo = (ListView) findViewById(R.id.listView2);
requestComplete(arrayMain);
It is better if you just put it right after call to setContentView() just to make sure this.listInfo holds valid ListView instance.

SetListAdapter works only at debug mode

I am working on an app which performs (in an AsyncTask) a query to a remote server obtaining a JSON string.
To show the data on my ListView i have extended an ArrayAdapter.
When i execute my app, from the LogCat i can see that data is retrieved correctly but not shown in the ListView.
The only way i have to make everything work (and data be shown on the ListView) is by running the app in Debug mode, set a breakpoint on the line
myListView.setAdapter(myAdapter);
wait for a couple seconds and then resume the application.
After this procedure, everything works correctly.
Why is this happening?
Is the AsyncTask the right way for such a long operation, or should I use some other approach (but i don't know which one!).
Here is the MainActivity code
public class MainActivityFragment extends Fragment {
private List<Station> stationList = new ArrayList<Station>();
private StationAdapter stationsAdapter;
private ProgressDialog pd;
private String LOG_TAG = "ProvaAsyncTask";
public MainActivityFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
mioAsync mioTask = new mioAsync();
mioTask.execute();
stationsAdapter = new StationAdapter(stationList, getActivity());
ListView stationsListView = (ListView) rootView.findViewById(R.id.miaListView);
stationsListView.setAdapter(stationsAdapter);
return rootView;
}
public class mioAsync extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
// Creo la ProgressDialog che precede il caricamento dei dati
pd = new ProgressDialog(getActivity());
pd.setMessage(MainActivityFragment.this.getString(R.string.preloader_stations_list));
pd.show();
}
#Override
protected Void doInBackground(Void... params) {
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
String forecastJsonStr = null;
try {
URL url = new URL("*remoteserver*");
// Create the request to the server, and open the connection
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();
// Read the input stream into a String
InputStream inputStream = urlConnection.getInputStream();
StringBuffer buffer = new StringBuffer();
if (inputStream == null) {
// Nothing to do.
return null;
}
reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
}
if (buffer.length() == 0) {
// Stream was empty. No point in parsing.
return null;
}
forecastJsonStr = buffer.toString();
} catch (IOException e) {
Log.e(LOG_TAG, "Error ", e);
return null;
} finally{
if (urlConnection != null) {
urlConnection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (final IOException e) {
Log.e(LOG_TAG, "Error closing stream", e);
}
}
}
try{
getStationsListFromJson(forecastJsonStr);
} catch (JSONException e) {
Log.e(LOG_TAG, e.getMessage(), e);
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
pd.dismiss();
}
private void getStationsListFromJson(String stationsJsonStr) throws JSONException {
JSONArray stationsArray = new JSONArray(stationsJsonStr);
String nomeStaz;
String numSat;
stationList.clear();
for (int i = 0; i < stationsArray.length(); i++) {
JSONObject j = stationsArray.optJSONObject(i);
Iterator it = j.keys();
while (it.hasNext()) {
String n = it.next().toString();
numSat = j.getString(n) + " stazioni";
n = it.next().toString();
nomeStaz = j.getString(n);
stationList.add(new Station(nomeStaz, numSat));
}
}
}
}
}
The JSON string i get in return is like this
[{"nome":"Station1","satelliti":"11"},{"nome":"Station2","satelliti":"9"},{"nome":"Station3","satelliti":"8"}]
Here is where i extend the ArrayList
public class StationAdapter extends ArrayAdapter<Station> {
private List<Station> stationsList;
private Context context;
public StationAdapter(List<Station> lista, Context cont){
super(cont, R.layout.listitems, lista);
this.stationsList = lista;
this.context = cont;
}
public int getCount() {
return stationsList.size();
}
public Station getItem(int position) {
return stationsList.get(position);
}
public long getItemId(int position) {
return stationsList.get(position).hashCode();
}
public View getView(int position, View convertView, ViewGroup parent){
View v = convertView;
StationHolder holder = new StationHolder();
// controllo che il convertview non sia null
if (convertView == null){
// This a new view we inflate the new layout
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = inflater.inflate(R.layout.listitems, null);
// Now we can fill the layout with the right values
TextView stationName = (TextView) v.findViewById(R.id.testataUno);
TextView satellitesNumber = (TextView) v.findViewById(R.id.testataDue);
holder.stationNameView = stationName;
holder.satellitesNumberView = satellitesNumber;
v.setTag(holder);
} else {
holder = (StationHolder) v.getTag();
}
Station p = stationsList.get(position);
holder.stationNameView.setText(p.getName());
holder.satellitesNumberView.setText("" + p.getSatellites());
return v;
}
/* *********************************
* We use the holder pattern
* It makes the view faster and avoid finding the component
* **********************************/
private static class StationHolder {
public TextView stationNameView;
public TextView satellitesNumberView;
}
}
Here is the Station code
public class Station {
private String name;
private String satellites;
public Station(String nome, String satelliti){
this.name = nome;
this.satellites = satelliti;
}
public String getName(){
return this.name;
}
public String getSatellites(){
return this.satellites;
}
public void setName(String nome){
this.name = nome;
}
public void setSatellites(String satelliti){
this.satellites = satelliti;
}
}

You got the flow broken. It works in debug mode only because you stop execution of UI thread on your breakpoint, but line before your breakpoint you fired AsyncTask, and as this is not stopped, it downloads the data while you enjoy your breakpoint. You most likely assumed that AsyncTask (which is abbreviation of Asynchronous Task) is... well... synchronous. It's not. Your main code will not wait for asynctask,it will start it and continue. You need to rework your code and in asynctask's onPostExecute() method update your dataset based on downloaded content and then call notifyDatasetChanged() on your list's adapter. That should trigger list refresh.

How to delete a list item from listview in android eclipse by clicking a button

I need to delete a list item from listview on clicking a delete button in android eclipse. The list values are populated from mysql database(JSON), so on deleting, I need to delete the same from database also.
Here is my main Activity; I need to delete a listitem from a listview on clicking a delete button on each item in the listview:
public class MainActivity extends Activity implements AsyncResponse2 {
private ProgressDialog dialog;
ListView l1;
//for getting count
TextView count;
private static final String TAG_COUNT = "cnt";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE); //to hide title bar
setContentView(R.layout.activity_main);
l1=(ListView)findViewById(R.id.listView1);
/** Reference to the delete button of the layout main.xml */
Button btnDel = (Button) findViewById(R.id.deleteid);
initView();
//str for getting count
count=(TextView)findViewById(R.id.countid);
//to display count while loading(so outside buttonclick)
String key1 = "saasvaap123";
String signupid1 = "8";
String url2 = "http://gooffers.in/omowebservices/index.php/webservice/Public_User/saved_offers_list?";
//http://gooffers.in/omowebservices/index.php/webservice/Public_User/saved_offers_list?key=saasvaap123&signup_id=8
//put the below lines outside button onclick since we load the values into edittext when opening the app
CustomHttpClient2 task2 = new CustomHttpClient2();
task2.execute(url2,key1,signupid1);
task2.delegate = MainActivity.this;
//end
}
//str getting count
//str customhttp2
private class CustomHttpClient2 extends AsyncTask<String, String, String>{
public AsyncResponse2 delegate=null;
private String msg;
#Override
protected void onPostExecute(String result2) {
// TODO Auto-generated method stub
super.onPostExecute(result2);
delegate.processFinish2(result2);
}
#Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
}
#Override
protected String doInBackground(String... params) {
if(params == null) return null;
// get url from params
String url2 = params[0];
String key1 = params[1];
String signupid1 = params[2];
ArrayList<NameValuePair> postParameters;
postParameters = new ArrayList<NameValuePair>();
postParameters.add(new BasicNameValuePair("key",key1));
postParameters.add(new BasicNameValuePair("signup_id",signupid1));
try {
// create http connection
HttpClient client = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url2);
httppost.setEntity(new UrlEncodedFormEntity(postParameters));
// connect
HttpResponse response = client.execute(httppost);
// get response
HttpEntity entity = response.getEntity();
if(entity != null){
return EntityUtils.toString(entity);
}
else{
return "No string.";
}
}
catch(Exception e){
return "Network problem";
}
}
}
public void processFinish2 (String output2){
Toast.makeText(MainActivity.this,output2, Toast.LENGTH_SHORT).show();
try{
//str
JSONObject jsonResponse = new JSONObject(output2);
JSONArray aJson = jsonResponse.getJSONArray("gen_off");
// create apps list
for(int i=0; i<aJson.length(); i++) {
JSONObject json = aJson.getJSONObject(i);
//end
//str
String strCount = json.getString(TAG_COUNT);
count.setText(strCount);//setting name to original name text
//end
}
}catch (JSONException e) {
Toast.makeText(MainActivity.this,"Exception caught!", Toast.LENGTH_SHORT).show();
}
}
//end getting count
private void initView() {
// show progress dialog
// dialog = ProgressDialog.show(this, "", "Loading...");
String key="saasvaap123";
String signup_id="8";
String url = "http://gooffers.in/omowebservices/index.php/webservice/Public_User/saved_offers_list?";
FetchDataTask task = new FetchDataTask();
task.execute(url,key,signup_id);
}
public class FetchDataTask extends AsyncTask<String, Void, String>{
// private final FetchDataListener listener;
private String msg;
#Override
protected String doInBackground(String... params) {
if(params == null) return null;
// get url from params
String url = params[0];
String key1 = params[1];
String signupid1 = params[2];
ArrayList<NameValuePair> postParameters;
postParameters = new ArrayList<NameValuePair>();
postParameters.add(new BasicNameValuePair("key",key1));
postParameters.add(new BasicNameValuePair("signup_id",signupid1));
//str
try {
// create http connection
HttpClient client = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url);
httppost.setEntity(new UrlEncodedFormEntity(postParameters));
// connect
HttpResponse response = client.execute(httppost);
// get response
HttpEntity entity = response.getEntity();
if(entity != null){
return EntityUtils.toString(entity);
}
else{
return "No string.";
}
}
catch(Exception e){
return "Network problem";
}
}
//end
//
#Override
protected void onPostExecute(String sJson) {
try {
JSONObject jsonResponse = new JSONObject(sJson);
JSONArray aJson = jsonResponse.getJSONArray("gen_off");
Toast.makeText(MainActivity.this, aJson.toString(),Toast.LENGTH_SHORT).show();
// create apps list
List<SavedOffers> apps = new ArrayList<SavedOffers>();
for(int i=0; i<aJson.length(); i++) {
JSONObject json = aJson.getJSONObject(i);
SavedOffers app = new SavedOffers();
app.setTitle(json.getString("title"));
app.setOriginalRate(json.getString("price"));
app.setOfferRate(json.getString("off_price"));
app.setPercentage(json.getString("percent"));
app.setSavings(json.getString("savings"));
app.setUrl(json.getString("image"));
// add the app to apps list
apps.add(app);
}
SavedOffersAdapter adapter = new SavedOffersAdapter(MainActivity.this, apps);
// set the adapter to list
l1.setAdapter(adapter);
//for delete
// adapter.notifyDataSetChanged();
/** Defining a click event listener for the button "Delete" */
Button btnDel = (Button) findViewById(R.id.deleteid);
OnClickListener listenerDel = new OnClickListener() {
#Override
public void onClick(View v) {
/** Getting the checked items from the listview */
SparseBooleanArray checkedItemPositions = l1.getCheckedItemPositions();
int itemCount = l1.getCount();
for(int i=itemCount-1; i >= 0; i--){
if(checkedItemPositions.get(i)){
adapter.remove(l1.get(i));
}
}
checkedItemPositions.clear();
adapter.notifyDataSetChanged();
}
};
/** Setting the event listener for the delete button */
btnDel.setOnClickListener(listenerDel);
/** Setting the adapter to the ListView */
l1.setAdapter(adapter); //end delete
//notify the activity that fetch data has been complete
// if(listener != null) listener.onFetchComplete(apps);
} catch (JSONException e) {
// msg = "Invalid response";
// if(listener != null) listener.onFetchFailure(msg);
// return;
}
}
/**
* This function will convert response stream into json string
* #param is respons string
* #return json string
* #throws IOException
*/
public String streamToString(final InputStream is) throws IOException{
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
}
catch (IOException e) {
throw e;
}
finally {
try {
is.close();
}
catch (IOException e) {
throw e;
}
}
return sb.toString();
}
}
}
// this is my adapter class , I think change is only needed in main activity
// , I need to delete a specific list item from listview on clicking the delete button
public class SavedOffersAdapter extends ArrayAdapter<SavedOffers>{
private List<SavedOffers> items;
Bitmap bitmap;
ImageView image;
public SavedOffersAdapter(Context context, List<SavedOffers> items) {
super(context, R.layout.app_custom_list, items);
this.items = items;
}
#Override
public int getCount() {
return items.size();
}
private class ViewHolder {
//TextView laptopTxt;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// ViewHolder holder;//added
View v = convertView;
if(v == null) {
LayoutInflater li = LayoutInflater.from(getContext());
v = li.inflate(R.layout.app_custom_list, null);
}
SavedOffers app = items.get(position);
if(app != null) {
TextView productName = (TextView)v.findViewById(R.id.nameid);
TextView originalRate = (TextView)v.findViewById(R.id.originalid);
originalRate.setPaintFlags(originalRate.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
TextView offerRate = (TextView)v.findViewById(R.id.offerid);
TextView percentage = (TextView)v.findViewById(R.id.discountid);
TextView savings = (TextView)v.findViewById(R.id.savingsid);
image =(ImageView)v.findViewById(R.id.prctimgid);
if(productName != null) productName.setText(app.getTitle());
if(originalRate != null) originalRate.setText(app.getOriginalRate());
if(offerRate != null) offerRate.setText(app. getOfferRate());
if(percentage != null) percentage.setText(app. getPercentage());
if(savings != null) savings.setText(app. getSavings());
if(image!=null){
new DownloadImageTask(image).execute(app.getUrl());
}
}
return v;
}

In your listviews adapter's getView method you link to the button on the layout your inflating and just attach a setOnClickListener... to the button and have it remove that item from your list or array that your adapter uses and then notifyDataHasChanged.
Delete that item from items in that position.
So 1. you want to delete the item from the ListView
2. you want to delete the item from the SQL DB.
The first one is very easy, but you kind of need to know the underlining adapter and how it serves data to your ListView. When you instantiate a BaseAdapter for the ListView you pass in a List or an array. This array will be the data your BaseAdapter serves to your ListView, each view in the listview will be showing an element from the array (done in getView()). If you dynamically delete one of those items, then adjust your array (or just use a List and it's .remove(), and finally notifyDataSetChanged(); your BaseAdapter will refresh your list without that View (or rather that View will be replaced with the new one). So for instance below I pass in a List<WeatherLocation> (WeatherLocation is a containing class that has weather stuff for a particular area (city, zipcode, degree"Biddeford", 04005, 72) to my BaseAdapter.
// Instantiate ListView
ListView lvLocations = (ListView) findViewById(R.id.lvLocations);
// Instantiate our BaseAdapter (pass in the List<WeatherLocation>)
WeatherLocationAdapter mWeatherLocationAdapter = new WeatherLocationAdapter(savedList, this, R.layout.view_weather_location);
lvLocations.setAdapter(mWeatherLocationAdapter);
This is an example of a regular ListView setting an Adapter to a custom BaseAdapter.
The BaseAdapter is so simple, that really the only method you care about (majorly) is the getView() method.
R.layout.view_weather_location is just a `LinearLayout` I made, it has 3 TextViews in it that I tie (show) my data with, by attaching data to those TextViews in the `getView()` method of the `BaseAdapter`. You would put a `Button there and tie it to what you want (to delete the data item)`.
public class WeatherLocationAdapter extends BaseAdapter{
private List <WeatherLocation> mLocations;
private Context mContext;
private int rowForLocationToInflate;
private LayoutInflater inflater;
public WeatherLocationAdapter(List<WeatherLocation> mLocations, Context mContext, int rowForLocationToInflate) {
this.mLocations = mLocations;
this.mContext = mContext;
this.rowForLocationToInflate = rowForLocationToInflate;
inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
//TODO just built up layout now must tie to it.
private void addLocation(WeatherLocation newLocation){
mLocations.add(newLocation);
//TODO maybe invalidate after adding new item.
}
#Override
public int getCount() {
return mLocations.size();
}
#Override
public WeatherLocation getItem(int position) {
return mLocations.get(position);
}
#Override
public long getItemId(int position) {
return 0;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
//TODO build a viewholder
View rowView = inflater.inflate(rowForLocationToInflate, parent, false);
TextView tvZipcode = (TextView) rowView.findViewById(R.id.tvZipCode);
TextView tvCity = (TextView) rowView.findViewById(R.id.tvCity);
TextView tvTemp = (TextView) rowView.findViewById(R.id.tvDegree);
tvZipcode.setText(mLocations.get(position).getZipcode());
tvCity.setText(mLocations.get(position).getCity());
tvTemp.setText(String.valueOf(mLocations.get(position).getTemperature()));
// If you had a Button in your LinearLayout you were attaching to you that you wanted to delete that view/item with, it would look something like this in my case.
Button bDel = (Button) row.findViewById(R.id.bDel);
bDel.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
mLocations.remove(position);
}
});
return rowView;
}
}
In the onClick you would also remove the item from the SQL db. I can show that too, but I feel you have some coding to do as it stands.

android button refresh

I am building a android-based app to implement twitter search function. The button click only works for the first. If i change the search term and click the button again, it fails to refresh. Anyone can give me a hint?
`public class TwitterSActivity extends Activity implements OnClickListener{
EditText etQuery;
Button btnQuery;
class Tweet{
public String username;
public String message;
public String image_url;
}
ArrayList<Tweet> tweets = new ArrayList<Tweet>();
#Override
public void onCreate(Bundle savedInstanceState) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
etQuery = (EditText) findViewById (R.id.et);
btnQuery = (Button) findViewById (R.id.btn);
btnQuery.setOnClickListener(this);
}
#Override
public void onClick(View v){
if(v.getId() == R.id.btn){
Toast.makeText(this, "Query submitted", Toast.LENGTH_LONG).show();
Getdata getdata = new Getdata();
String returned = null;
String searchTerm = etQuery.getText().toString();
try {
returned = getdata.getInternetData(searchTerm);
} catch (Exception e) {
e.printStackTrace();
}
try{
JSONObject jo = new JSONObject(returned);
JSONArray ja = jo.getJSONArray("results");
for(int i=0; i<ja.length(); i++){
JSONObject job = ja.getJSONObject(i);
Tweet tt = new Tweet();
tt.username = job.getString("from_user");
tt.message = job.getString("text");
tt.image_url = job.getString("profile_image_url");
tweets.add(tt);
}
}
catch(JSONException e){
Log.e("log_tag", "Error parsing data: "+e.toString());
}
ListView lv = (ListView) findViewById(R.id.listView1);
class FancyAdapter extends ArrayAdapter<Tweet> {
public FancyAdapter() {
super(TwitterSActivity.this, android.R.layout.simple_list_item_1, tweets);
}
public View getView(int position, View convertView, ViewGroup parent){
ViewHolder holder;
if(convertView == null){
LayoutInflater inflater = getLayoutInflater();
convertView = inflater.inflate(R.layout.listitem, null);
holder = new ViewHolder(convertView);
convertView.setTag(holder);
}
else
{
holder = (ViewHolder)convertView.getTag();
}
holder.populatefrom(tweets.get(position));
return(convertView);
}
class ViewHolder {
public TextView username = null;
public TextView message = null;
public ImageView image = null;
ViewHolder(View listitem){
username = (TextView)listitem.findViewById(R.id.username);
message = (TextView)listitem.findViewById(R.id.message);
image = (ImageView)listitem.findViewById(R.id.avatar);
}
void populatefrom(Tweet t){
username.setText(t.username);
message.setText(t.message);
image.setImageBitmap(getBitmap(t.image_url));
}
}
}
FancyAdapter ar = new FancyAdapter();
lv.setAdapter(ar);
}
}
public Bitmap getBitmap(String bitmapUrl) {
try {
URL url = new URL(bitmapUrl);
return BitmapFactory.decodeStream(url.openConnection().getInputStream());
}
catch(Exception e) {return null;}
}`

Finally i figure it out, here is how I fix it:
I change ArrayList<Tweet> tweets = new ArrayList<Tweet>(); to final ArrayList<Tweet> tweets = new ArrayList<Tweet>();
and then move it under onClick() method. It works well without notifyDataSetChanged().