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how to select first index in listview onCreate()? [duplicate]

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What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 4 years ago.
I am trying to select the first index in listview on first load onCreate. I've try the listView.setSelection(0) but some error occur. this is my code...
public class QandAPractice extends AppCompatActivity {
String qsid;
ListView listView;
ArrayList<String> myqid;
RadioButton r1,r2,r3,r4;
String txtcontent, txtTimer,txtAnskey,txtImg, txtA, txtB, txtC, txtD, txtID;
private static final String TAG_QID = "id";
private static final String TAG_TITLE = "content";
private static final String TAG_TIMER = "timer";
private static final String TAG_IMAGE = "images";
private static final String TAG_QSID = "qsid";
private static final String TAG_KEY = "key";
private static final String TAG_A = "A";
private static final String TAG_B = "B";
private static final String TAG_C = "C";
private static final String TAG_D = "D";
ArrayList<HashMap<String, String>> questions;
Dialog quizDialog;
public int i = 60;
public int loadindex = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_qand_apractice);
questions = new ArrayList<>();
myqid = new ArrayList<>();
Bundle b = getIntent().getExtras();
setTitle(b.getString("subject"));
qsid = b.getString("qsid");
quizDialog = new Dialog(this,android.R.style.Theme_Black_NoTitleBar_Fullscreen);
listView = findViewById(R.id.lvquestions);
getJSON(Constants.ROOT_URL+"mobile_question_index.php?qsid="+qsid);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
txtID = ((TextView) view.findViewById(R.id.quiz_id)).getText()
.toString();
txtcontent = ((TextView) view.findViewById(R.id.quiz_content)).getText()
.toString();
txtTimer = ((TextView) view.findViewById(R.id.quiz_timer)).getText()
.toString();
txtAnskey = ((TextView) view.findViewById(R.id.quiz_key)).getText()
.toString();
txtA = ((TextView) view.findViewById(R.id.quiz_A)).getText()
.toString();
txtB = ((TextView) view.findViewById(R.id.quiz_B)).getText()
.toString();
txtC = ((TextView) view.findViewById(R.id.quiz_C)).getText()
.toString();
txtD = ((TextView) view.findViewById(R.id.quiz_D)).getText()
.toString();
txtImg = ((TextView) view.findViewById(R.id.quiz_image)).getText()
.toString();
showQuiz();
}
});
listView.setSelection(0);
listView.getSelectedView().setSelected(true);
}
private void getJSON(final String urlWebService) {
class GetJSON extends AsyncTask<Void, Void, String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
try {
loadIntoListView(s);
} catch (JSONException e) {
e.printStackTrace();
}
}
#Override
protected String doInBackground(Void... voids) {
try {
URL url = new URL(urlWebService);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
StringBuilder sb = new StringBuilder();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
String json;
while ((json = bufferedReader.readLine()) != null) {
sb.append(json + "\n");
}
return sb.toString().trim();
} catch (Exception e) {
return null;
}
}
}
GetJSON getJSON = new GetJSON();
getJSON.execute();
}
private void loadIntoListView(String json) throws JSONException {
JSONArray jsonArray = new JSONArray(json);
//String[] question = new String[jsonArray.length()];
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject obj = jsonArray.getJSONObject(i);
String id = obj.getString(TAG_QID);
String content = obj.getString(TAG_TITLE);
String image = obj.getString(TAG_IMAGE);
String a = obj.getString(TAG_A);
String b = obj.getString(TAG_B);
String c = obj.getString(TAG_C);
String d = obj.getString(TAG_D);
String key = obj.getString(TAG_KEY);
String timer = obj.getString(TAG_TIMER);
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_QID,id);
map.put(TAG_TITLE,content);
map.put(TAG_IMAGE,image);
map.put(TAG_A,a);
map.put(TAG_B,b);
map.put(TAG_C,c);
map.put(TAG_D,d);
map.put(TAG_KEY,key);
map.put(TAG_TIMER,timer);
myqid.add(id);
questions.add(map);
}
// ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, question);
SimpleAdapter adapter = new SimpleAdapter(
QandAPractice.this, questions,
R.layout.quizlayout, new String[]{TAG_QID,
TAG_TITLE, TAG_IMAGE,TAG_A,TAG_B,TAG_C,TAG_D,TAG_KEY,TAG_TIMER},
new int[]{R.id.quiz_id, R.id.quiz_content, R.id.quiz_image,R.id.quiz_A,R.id.quiz_B,
R.id.quiz_C,R.id.quiz_D,R.id.quiz_key,R.id.quiz_timer});
/* AtomicReference<ListAdapter> la =
new AtomicReference<>(new ListAdapter(getApplicationContext(), questions));*/
listView.setAdapter(adapter);
}
this is the Error fetch in debug logcat..
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setSelected(boolean)' on a null object reference
at com.example.jhan08.engineeringexclusivereviewer.QandAPractice.onCreate(QandAPractice.java:90)
at android.app.Activity.performCreate(Activity.java:6351)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1114)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2470)
I've read some thread that has the same issue like mine. They use adapter to fix the issue but still in my case this error still occur. Any help is much appreciated.

Do Your Selection after you set Your Adapter to the Listview
private void loadIntoListView(String json) throws JSONException {
JSONArray jsonArray = new JSONArray(json);
//String[] question = new String[jsonArray.length()];
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject obj = jsonArray.getJSONObject(i);
String id = obj.getString(TAG_QID);
String content = obj.getString(TAG_TITLE);
String image = obj.getString(TAG_IMAGE);
String a = obj.getString(TAG_A);
String b = obj.getString(TAG_B);
String c = obj.getString(TAG_C);
String d = obj.getString(TAG_D);
String key = obj.getString(TAG_KEY);
String timer = obj.getString(TAG_TIMER);
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_QID,id);
map.put(TAG_TITLE,content);
map.put(TAG_IMAGE,image);
map.put(TAG_A,a);
map.put(TAG_B,b);
map.put(TAG_C,c);
map.put(TAG_D,d);
map.put(TAG_KEY,key);
map.put(TAG_TIMER,timer);
myqid.add(id);
questions.add(map);
}
// ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, question);
SimpleAdapter adapter = new SimpleAdapter(
QandAPractice.this, questions,
R.layout.quizlayout, new String[]{TAG_QID,
TAG_TITLE, TAG_IMAGE,TAG_A,TAG_B,TAG_C,TAG_D,TAG_KEY,TAG_TIMER},
new int[]{R.id.quiz_id, R.id.quiz_content, R.id.quiz_image,R.id.quiz_A,R.id.quiz_B,
R.id.quiz_C,R.id.quiz_D,R.id.quiz_key,R.id.quiz_timer});
/* AtomicReference<ListAdapter> la =
new AtomicReference<>(new ListAdapter(getApplicationContext(), questions));*/
listView.setAdapter(adapter);
listView.setSelection(0);
listView.getSelectedView().setSelected(true);
}

I think I got the main issue you have faced. You try to select an item before populating the list view. You need to set this after adapter added on the listview.
Add this lines after adding the adapter.
listView.setAdapter(adapter);
listView.setSelection(0);
listView.getSelectedView().setSelected(true);
or use
listView.setAdapter(adapter);
listView.setItemChecked(0, true)
This will show a toast message for first opening. This should be added after the adapter set.
Iterator myVeryOwnIterator = questions.get(0).keySet().iterator();
while(myVeryOwnIterator.hasNext()) {
String key=(String)myVeryOwnIterator.next();
String value=(String)meMap.get(key);
Toast.makeText(ctx, "Key: "+key+" Value: "+value, Toast.LENGTH_LONG).show();
}

getting AndroidRuntime: FATAL EXCEPTION: AsyncTask #1

I want to use AsyncTask to parse JSON data For that I have Created constructor of FetchWeatherTask in ForecastFragment
ForecastFragment.java
public class ForecastFragment extends Fragment {
private ArrayAdapter<String> mForecastAdapter;
public ForecastFragment() {
}
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Add this line in order for this fragment to handle menu events.
setHasOptionsMenu(true);
}
#Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.forecastfragment, menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_refresh) {
updateWeather();
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// The ArrayAdapter will take data from a source and
// use it to populate the ListView it's attached to.
mForecastAdapter =
new ArrayAdapter<String>(
getActivity(),// The current context (this activity)
R.layout.list_item_forecast,// The name of the layout ID.
R.id.tv_list_item_forecast, new ArrayList<String>()); // The ID of the textview to populate.
// Log.e("weekForecast", "forecastArray: " + forecastArray + "/n" + weekForecast);
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
ListView listView = (ListView) rootView.findViewById(R.id.listview_forecast);
listView.setAdapter(mForecastAdapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
String forecast = mForecastAdapter.getItem(position);
Intent intent = new Intent(getActivity(), DetailActivity.class)
.putExtra(Intent.EXTRA_TEXT, forecast);
startActivity(intent);
}
});
return rootView;
}
private void updateWeather() {
// FetchWeatherTask weatherTask = new FetchWeatherTask();
FetchWeatherTask weatherTask = new FetchWeatherTask(getActivity(), mForecastAdapter);
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getActivity());
String location = prefs.getString(getString(R.string.pref_location_key),
getString(R.string.pref_location_default));
weatherTask.execute(location);
}
#Override
public void onStart() {
super.onStart();
updateWeather();
}
FetchWeatherTask.java
public class FetchWeatherTask extends AsyncTask<String, Void, String[]> {
private final String LOG_TAG = FetchWeatherTask.class.getSimpleName();
private ArrayAdapter<String> mForecastAdapter;
private final Context mContext;
public FetchWeatherTask(Context context, ArrayAdapter<String> forecastAdapter) {
mContext = context;
mForecastAdapter = forecastAdapter;
}
private boolean DEBUG = true;
/* The date/time conversion code is going to be moved outside the asynctask later,
* so for convenience we're breaking it out into its own method now.
*/
private String getReadableDateString(long time) {
// Because the API returns a unix timestamp (measured in seconds),
// it must be converted to milliseconds in order to be converted to valid date.
Date date = new Date(time);
SimpleDateFormat format = new SimpleDateFormat("E, MMM d");
return format.format(date).toString();
}
/**
* Prepare the weather high/lows for presentation.
*/
private String formatHighLows(double high, double low) {
// Data is fetched in Celsius by default.
// If user prefers to see in Fahrenheit, convert the values here.
// We do this rather than fetching in Fahrenheit so that the user can
// change this option without us having to re-fetch the data once
// we start storing the values in a database.
SharedPreferences sharedPrefs =
PreferenceManager.getDefaultSharedPreferences(mContext);
String unitType = sharedPrefs.getString(
mContext.getString(R.string.pref_units_key),
mContext.getString(R.string.pref_units_metric));
if (unitType.equals(mContext.getString(R.string.pref_units_imperial))) {
high = (high * 1.8) + 32;
low = (low * 1.8) + 32;
} else if (!unitType.equals(mContext.getString(R.string.pref_units_metric))) {
Log.d(LOG_TAG, "Unit type not found: " + unitType);
}
// For presentation, assume the user doesn't care about tenths of a degree.
long roundedHigh = Math.round(high);
long roundedLow = Math.round(low);
String highLowStr = roundedHigh + "/" + roundedLow;
return highLowStr;
}
/**
* Helper method to handle insertion of a new location in the weather database.
*
* #param locationSetting The location string used to request updates from the server.
* #param cityName A human-readable city name, e.g "Mountain View"
* #param lat the latitude of the city
* #param lon the longitude of the city
* #return the row ID of the added location.
*/
long addLocation(String locationSetting, String cityName, double lat, double lon) {
long locationId;
// First, check if the location with this city name exists in the db
Cursor locationCursor = mContext.getContentResolver().query(
WeatherContract.LocationEntry.CONTENT_URI,
new String[]{WeatherContract.LocationEntry._ID},
WeatherContract.LocationEntry.COLUMN_LOCATION_SETTING + " = ?",
new String[]{locationSetting},
null);
if (locationCursor.moveToFirst()) {
int locationIdIndex = locationCursor.getColumnIndex(WeatherContract.LocationEntry._ID);
locationId = locationCursor.getLong(locationIdIndex);
} else {
// Now that the content provider is set up, inserting rows of data is pretty simple.
// First create a ContentValues object to hold the data you want to insert.
ContentValues locationValues = new ContentValues();
// Then add the data, along with the corresponding name of the data type,
// so the content provider knows what kind of value is being inserted.
locationValues.put(WeatherContract.LocationEntry.COLUMN_CITY_NAME, cityName);
locationValues.put(WeatherContract.LocationEntry.COLUMN_LOCATION_SETTING, locationSetting);
locationValues.put(WeatherContract.LocationEntry.COLUMN_COORD_LAT, lat);
locationValues.put(WeatherContract.LocationEntry.COLUMN_COORD_LONG, lon);
// Finally, insert location data into the database.
Uri insertedUri = mContext.getContentResolver().insert(
WeatherContract.LocationEntry.CONTENT_URI,
locationValues
);
// The resulting URI contains the ID for the row. Extract the locationId from the Uri.
locationId = ContentUris.parseId(insertedUri);
}
locationCursor.close();
// Wait, that worked? Yes!
return locationId;
}
/*
Students: This code will allow the FetchWeatherTask to continue to return the strings that
the UX expects so that we can continue to test the application even once we begin using
the database.
*/
String[] convertContentValuesToUXFormat(Vector<ContentValues> cvv) {
// return strings to keep UI functional for now
String[] resultStrs = new String[cvv.size()];
for (int i = 0; i < cvv.size(); i++) {
ContentValues weatherValues = cvv.elementAt(i);
String highAndLow = formatHighLows(
weatherValues.getAsDouble(WeatherEntry.COLUMN_MAX_TEMP),
weatherValues.getAsDouble(WeatherEntry.COLUMN_MIN_TEMP));
resultStrs[i] = getReadableDateString(
weatherValues.getAsLong(WeatherEntry.COLUMN_DATE)) +
" - " + weatherValues.getAsString(WeatherEntry.COLUMN_SHORT_DESC) +
" - " + highAndLow;
}
return resultStrs;
}
/**
* Take the String representing the complete forecast in JSON Format and
* pull out the data we need to construct the Strings needed for the wireframes.
* <p/>
* Fortunately parsing is easy: constructor takes the JSON string and converts it
* into an Object hierarchy for us.
*/
private String[] getWeatherDataFromJson(String forecastJsonStr,
String locationSetting)
throws JSONException {
// Now we have a String representing the complete forecast in JSON Format.
// Fortunately parsing is easy: constructor takes the JSON string and converts it
// into an Object hierarchy for us.
// These are the names of the JSON objects that need to be extracted.
// Location information
final String OWM_CITY = "city";
final String OWM_CITY_NAME = "name";
final String OWM_COORD = "coord";
// Location coordinate
final String OWM_LATITUDE = "lat";
final String OWM_LONGITUDE = "lon";
// Weather information. Each day's forecast info is an element of the "list" array.
final String OWM_LIST = "list";
final String OWM_PRESSURE = "pressure";
final String OWM_HUMIDITY = "humidity";
final String OWM_WINDSPEED = "speed";
final String OWM_WIND_DIRECTION = "deg";
// All temperatures are children of the "temp" object.
final String OWM_TEMPERATURE = "temp";
final String OWM_MAX = "max";
final String OWM_MIN = "min";
final String OWM_WEATHER = "weather";
final String OWM_DESCRIPTION = "main";
final String OWM_WEATHER_ID = "id";
try {
JSONObject forecastJson = new JSONObject(forecastJsonStr);
JSONArray weatherArray = forecastJson.getJSONArray(OWM_LIST);
JSONObject cityJson = forecastJson.getJSONObject(OWM_CITY);
String cityName = cityJson.getString(OWM_CITY_NAME);
JSONObject cityCoord = cityJson.getJSONObject(OWM_COORD);
double cityLatitude = cityCoord.getDouble(OWM_LATITUDE);
double cityLongitude = cityCoord.getDouble(OWM_LONGITUDE);
long locationId = addLocation(locationSetting, cityName, cityLatitude, cityLongitude);
// Insert the new weather information into the database
Vector<ContentValues> cVVector = new Vector<ContentValues>(weatherArray.length());
// OWM returns daily forecasts based upon the local time of the city that is being
// asked for, which means that we need to know the GMT offset to translate this data
// properly.
// Since this data is also sent in-order and the first day is always the
// current day, we're going to take advantage of that to get a nice
// normalized UTC date for all of our weather.
Time dayTime = new Time();
dayTime.setToNow();
// we start at the day returned by local time. Otherwise this is a mess.
int julianStartDay = Time.getJulianDay(System.currentTimeMillis(), dayTime.gmtoff);
// now we work exclusively in UTC
dayTime = new Time();
for (int i = 0; i < weatherArray.length(); i++) {
// These are the values that will be collected.
long dateTime;
double pressure;
int humidity;
double windSpeed;
double windDirection;
double high;
double low;
String description;
int weatherId;
// Get the JSON object representing the day
JSONObject dayForecast = weatherArray.getJSONObject(i);
// Cheating to convert this to UTC time, which is what we want anyhow
dateTime = dayTime.setJulianDay(julianStartDay + i);
pressure = dayForecast.getDouble(OWM_PRESSURE);
humidity = dayForecast.getInt(OWM_HUMIDITY);
windSpeed = dayForecast.getDouble(OWM_WINDSPEED);
windDirection = dayForecast.getDouble(OWM_WIND_DIRECTION);
// Description is in a child array called "weather", which is 1 element long.
// That element also contains a weather code.
JSONObject weatherObject =
dayForecast.getJSONArray(OWM_WEATHER).getJSONObject(0);
description = weatherObject.getString(OWM_DESCRIPTION);
weatherId = weatherObject.getInt(OWM_WEATHER_ID);
// Temperatures are in a child object called "temp". Try not to name variables
// "temp" when working with temperature. It confuses everybody.
JSONObject temperatureObject = dayForecast.getJSONObject(OWM_TEMPERATURE);
high = temperatureObject.getDouble(OWM_MAX);
low = temperatureObject.getDouble(OWM_MIN);
ContentValues weatherValues = new ContentValues();
weatherValues.put(WeatherEntry.COLUMN_LOC_KEY, locationId);
weatherValues.put(WeatherEntry.COLUMN_DATE, dateTime);
weatherValues.put(WeatherEntry.COLUMN_HUMIDITY, humidity);
weatherValues.put(WeatherEntry.COLUMN_PRESSURE, pressure);
weatherValues.put(WeatherEntry.COLUMN_WIND_SPEED, windSpeed);
weatherValues.put(WeatherEntry.COLUMN_DEGREES, windDirection);
weatherValues.put(WeatherEntry.COLUMN_MAX_TEMP, high);
weatherValues.put(WeatherEntry.COLUMN_MIN_TEMP, low);
weatherValues.put(WeatherEntry.COLUMN_SHORT_DESC, description);
weatherValues.put(WeatherEntry.COLUMN_WEATHER_ID, weatherId);
cVVector.add(weatherValues);
}
// add to database
if (cVVector.size() > 0) {
ContentValues[] cvArray = new ContentValues[cVVector.size()];
cVVector.toArray(cvArray);
mContext.getContentResolver().bulkInsert(WeatherEntry.CONTENT_URI, cvArray);
}
// Sort order: Ascending, by date.
String sortOrder = WeatherEntry.COLUMN_DATE + " ASC";
Uri weatherForLocationUri = WeatherEntry.buildWeatherLocationWithStartDate(
locationSetting, System.currentTimeMillis());
// Students: Uncomment the next lines to display what what you stored in the bulkInsert
Cursor cur = mContext.getContentResolver().query(weatherForLocationUri,
null, null, null, sortOrder);
cVVector = new Vector<ContentValues>(cur.getCount());
if (cur.moveToFirst()) {
do {
ContentValues cv = new ContentValues();
DatabaseUtils.cursorRowToContentValues(cur, cv);
cVVector.add(cv);
} while (cur.moveToNext());
}
Log.d(LOG_TAG, "FetchWeatherTask Complete. " + cVVector.size() + " Inserted");
String[] resultStrs = convertContentValuesToUXFormat(cVVector);
return resultStrs;
} catch (JSONException e) {
Log.e(LOG_TAG, e.getMessage(), e);
e.printStackTrace();
}
return null;
}
#Override
protected String[] doInBackground(String... params) {
// If there's no zip code, there's nothing to look up. Verify size of params.
if (params.length == 0) {
return null;
}
String locationQuery = params[0];
// These two need to be declared outside the try/catch
// so that they can be closed in the finally block.
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
// Will contain the raw JSON response as a string.
String forecastJsonStr = null;
String format = "json";
String units = "metric";
int numDays = 14;
try {
// Construct the URL for the OpenWeatherMap query
// Possible parameters are avaiable at OWM's forecast API page, at
// http://openweathermap.org/API#forecast
final String FORECAST_BASE_URL =
"http://api.openweathermap.org/data/2.5/forecast/daily?";
final String QUERY_PARAM = "q";
final String FORMAT_PARAM = "mode";
final String UNITS_PARAM = "units";
final String DAYS_PARAM = "cnt";
final String APPID_PARAM = "APPID";
Uri builtUri = Uri.parse(FORECAST_BASE_URL).buildUpon()
.appendQueryParameter(QUERY_PARAM, params[0])
.appendQueryParameter(FORMAT_PARAM, format)
.appendQueryParameter(UNITS_PARAM, units)
.appendQueryParameter(DAYS_PARAM, Integer.toString(numDays))
.appendQueryParameter(APPID_PARAM, BuildConfig.OPEN_WEATHER_MAP_API_KEY)
.build();
URL url = new URL(builtUri.toString());
// Create the request to OpenWeatherMap, 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) {
// Since it's JSON, adding a newline isn't necessary (it won't affect parsing)
// But it does make debugging a *lot* easier if you print out the completed
// buffer for debugging.
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);
// If the code didn't successfully get the weather data, there's no point in attemping
// to parse it.
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 {
return getWeatherDataFromJson(forecastJsonStr, locationQuery);
} catch (JSONException e) {
Log.e(LOG_TAG, e.getMessage(), e);
e.printStackTrace();
}
// This will only happen if there was an error getting or parsing the forecast.
return null;
}
#Override
protected void onPostExecute(String[] result) {
if (result != null && mForecastAdapter != null) {
mForecastAdapter.clear();
for (String dayForecastStr : result) {
mForecastAdapter.add(dayForecastStr);
}
// New data is back from the server. Hooray!
}
}}
Though I have created constructor of FetchWeatherTask and initialized the values but still I am getting Following error:
http://i.stack.imgur.com/6elr4.png

Your
locationCursor
is null in
addLocation
method

Android: sort by date in the JSON data

I am new to Android. I'm trying to sort by the date in the JSON data, but nothing works. I'm not even getting an error. I've tried so many different ways, but its not working.
I did a lot of searching but could not figure out how to implement this. How can I sort this by the days column? Thank you in advance.
Here's my code
public class ParseJSONTask extends AsyncTask< Void , Void , Void > {
public Handler handler = new Handler();
public Activity act = null;
private static String TAG_SERVICES = "services";
private static String TAG_ID = "id";
private static String TAG_COMMAND = "command";
private static String TAG_DAYS = "days";
private static String TAG_HOURS = "hours";
private static String TAG_OSMS = "osms";
private static String TAG_ISMS = "isms";
private static String TAG_TIMEOUT = "timeout";
public String SMS_SENT = "SMS Gönderildi";
public String SMS_DELIVERED = "SMS İletildi";
public String serviceString = "";
ArrayList<ServiceData> services;
#Override
public void onPreExecute() {
super.onPreExecute();
services = new ArrayList<ServiceData>();
}
#Override
public Void doInBackground(Void... params) {
WebServiceHandler webServiceHandler = new WebServiceHandler();
String JsonStr = webServiceHandler.getJSONData("http://jsonblob.com/55e34310e4b01190df36e861");
try {
JSONObject jsonObject = new JSONObject(JsonStr);
final JSONArray contactsJSON = jsonObject.getJSONArray(TAG_SERVICES);
for (int i = 0; i < contactsJSON.length(); i++) {
ServiceData aServiceData = new ServiceData();
//json parse istedimiz veriyi kullanabiliriz.
JSONObject serviceObject = contactsJSON.getJSONObject(i);
aServiceData.id = serviceObject.getString(TAG_ID);
aServiceData.command = serviceObject.getString(TAG_COMMAND);
aServiceData.days = serviceObject.getString(TAG_DAYS);
aServiceData.hours = serviceObject.getString(TAG_HOURS);
aServiceData.osms = serviceObject.getString(TAG_OSMS);
aServiceData.isms = serviceObject.getString(TAG_ISMS);
aServiceData.timeout = serviceObject.getString(TAG_TIMEOUT);
String input = aServiceData.days + " " + aServiceData.hours;
Date date = new SimpleDateFormat("yyyy-MM-dd HH:mm").parse(input);
long milliseconds = date.getTime();
final long millisecondsFromNow = milliseconds - (new Date()).getTime();
aServiceData.milliseconds = milliseconds;
services.add(aServiceData);
if(millisecondsFromNow > 0) {
new DateSendSMS().onCreate(aServiceData.days, aServiceData.hours, aServiceData.osms, aServiceData.command);
Thread.sleep(Integer.parseInt(aServiceData.timeout) * 60000);
}
//Timeout aşağı kısımda sürelendirilecek
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
String serviceString = "";
for (ServiceData aServiceData:services){
serviceString+=aServiceData.toString();
}
Collections.sort(services, new Comparator<ServiceData>() {
#Override
public int compare(ServiceData t1, ServiceData t2) {
return t1.milliseconds <= t2.milliseconds ? -1 : 1;
}
});
// here is sorted data
for (ServiceData aServiceData : services) {
// move DateSendSMS here. above you can add additional logic about millis
new DateSendSMS().onCreate(aServiceData.days, aServiceData.hours, aServiceData.osms, aServiceData.command);
Log.d("+++++", aServiceData.toString());
}
}
}
ServiceData Class:
public static class ServiceData {
public long milliseconds;
public String id = "";
public String command = "";
public String days = "";
public String hours = "";
public String osms = "";
public String isms = "";
public String timeout = "";
#Override
public String toString() {
return id + ", " + command + ", " + days + ", " + hours + ", " + osms + ", " + isms
+ ", " + timeout + "\n \n ";
}
}

Add time field to ServiceData class
ServiceDate {
...
long milliseconds;
...
}
Fill this field in for loop:
long milliseconds = date.getTime();
aServiceData.milliseconds = milliseconds;
Sort services in onPostExecute
Collections.sort(services, new Comparator<ServiceData>() {
#Override
public int compare(ServiceData t1, ServiceData t2) {
return t1.milliseconds <= t2.milliseconds ? -1 : 1;
}
});

I am not sure you can directly sort Json Data (I dont know weather there is a library that will actually do it - if so go for it). I Suggest you to put all the ServiceData into a collection (Which you do at the moment) and then Sort it.
You can write your own sorting algorithm or you can use a Java Collections library to do the sorting by implimention Comparable on your ServiceData class or using a Comparable and them you can use Colletions.sort() to sort your list.
Here is a good tutorial.

Google Maps And ListView in one activity in android?

I am trying to fit a Google Maps View and a ListView into one activity. The MapsView shall take 2/3 of the upper side, and the list 1/3 of the lower side (in portrait).
in this way assume it as portrait:
Both, the MapsView and the ListView, will receive the same JSON information, they will get onCreate(). I was already able to fit the MapsView on 2/3 of the screen, but the ListView wont receive any data. Can someone tell me, how to adress a ListView correct, when the superclass isnt ListActivity?
here is my code:
// url to make request
private static String url = ""; //here pass the url
// JSON Node names
private static final String TAG_LOCATION = "location";
private static final String TAG_LOCATION1= "location";
private static final String TAG_LOCATION_ID = "LocationID";
private static final String TAG_NAME = "Name";
private static final String TAG_PHONE = "Phone";
private static final String TAG_FORMATTED_PHONE = "FormattedPhone";
private static final String TAG_ADDRESS = "Address";
private static final String TAG_CROSS_STREET = "CrossStreet";
private static final String TAG_LAT = "Lat";
private static final String TAG_LNG = "Lng";
private static final String TAG_DISTANCE= "Distance";
private static final String TAG_POSTAL_CODE = "PostalCode";
private static final String TAG_CITY = "City";
private static final String TAG_STATE = "State";
private static final String TAG_COUNTRY= "Country";
// contacts JSONArray
JSONArray location = null;
JSONObject location1=null;
ListView locationList;
private MapView mapView;
LocationManager lm;
LocationListener locationListener;
MapController mapController;
private ListAdapter adapter;
private static final double lat = 11.9333;
private static final double lng = 108.417;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.view_map);
locationList=( ListView)findViewById(R.id.list_Surroundings);
locationList.setAdapter(adapter);
// Hashmap for ListView
ArrayList<HashMap<String, String>> locationList = new ArrayList<HashMap<String, String>>();
// Creating JSON Parser instance
JSONParser jParser = new JSONParser();
// getting JSON string from URL
JSONObject json = jParser.getJSONFromUrl(url);
try {
// Getting Array of Category
location=json.getJSONArray(TAG_LOCATION);
//looping through all categories
for(int i = 0; i < location.length(); i++){
JSONObject c = location.getJSONObject(i);
JSONObject c1=c.getJSONObject(TAG_LOCATION1);
// Storing each json item in variable
String LocationID = c1.getString(TAG_LOCATION_ID);
String Name = c1.getString(TAG_NAME);
String Phone = c1.getString(TAG_PHONE);
String FormattedPhone = c1.getString(TAG_FORMATTED_PHONE);
String Address = c1.getString(TAG_ADDRESS);
String CrossStreet = c1.getString(TAG_CROSS_STREET);
String Lat = c1.getString(TAG_LAT);
String Lng = c1.getString(TAG_LNG);
String Distance = c1.getString(TAG_DISTANCE);
String PostalCode = c1.getString(TAG_POSTAL_CODE);
String City = c1.getString(TAG_CITY);
String State = c1.getString(TAG_STATE);
String Country = c1.getString(TAG_COUNTRY);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_LOCATION_ID, LocationID);
map.put(TAG_NAME, Name);
map.put(TAG_PHONE, Phone);
map.put(TAG_FORMATTED_PHONE, FormattedPhone);
map.put(TAG_ADDRESS, Address);
map.put(TAG_CROSS_STREET, CrossStreet);
map.put(TAG_LAT, Lat);
map.put(TAG_LNG, Lng);
map.put(TAG_DISTANCE, Distance);
map.put(TAG_POSTAL_CODE, PostalCode);
map.put(TAG_CITY, City);
map.put(TAG_STATE, State);
map.put(TAG_COUNTRY, Country);
// adding HashList to ArrayList
locationList.add(map);
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
/**
* Updating parsed JSON data into ListView
* */
adapter = new SimpleAdapter(this, locationList,
R.layout.list_item,
new String[] { TAG_NAME }, new int[] {
R.id.name});
mapView = (MapView) findViewById(R.id.mapView);
mapView.setBuiltInZoomControls(true);
List mapOverlays = mapView.getOverlays();
Drawable drawable = this.getResources().getDrawable(
R.drawable.map_pin_red);
CustomItemizedOverlay itemizedOverlay = new CustomItemizedOverlay(
drawable, this);
GeoPoint point = new GeoPoint((int) (lat * 1E6), (int) (lng * 1E6));
OverlayItem overlayitem = new OverlayItem(point, "Hello",
"I'm in Athens, Greece!");
itemizedOverlay.addOverlay(overlayitem);
mapOverlays.add(itemizedOverlay);
mapController = mapView.getController();
mapController.animateTo(point);
mapController.setZoom(10);
lm=(LocationManager)getSystemService(Context.LOCATION_SERVICE);
locationListener= new MylocationListener();
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}
public class MylocationListener implements LocationListener{
#Override
public void onLocationChanged(Location loc) {
// TODO Auto-generated method stub
if(loc!=null){
Toast.makeText(getBaseContext(), "Location Changed : Lat:" +loc.getLatitude() + "Lng: " + loc.getLongitude(), Toast.LENGTH_SHORT).show();
}
GeoPoint point = new GeoPoint((int) (lat * 1E6), (int) (lng * 1E6));
mapController.animateTo(point);
mapController.setZoom(10);
}
#Override
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
#Override
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
#Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
}
#Override
protected boolean isRouteDisplayed() {
// TODO Auto-generated method stub
return false;
}
}

You have to create the adapter BEFORE setting it as the adapter of the ListView. Also, you have two variables named LocationList, which is generally bad practice. Try:
public void onCreate(Bundle savedInstanceState) {
// Hashmap for ListView
ArrayList<HashMap<String, String>> listOfLocations = new ArrayList<HashMap<String, String>>();
... // existing code here
adapter = new SimpleAdapter(this, listOfLocations,
R.layout.list_item,
new String[] { TAG_NAME }, new int[] {
R.id.name});
locationList.setAdapter(adapter);
}

How to get Latitude/Longitude from JSON responsed by google map apis

I am not able to properly extract out the latitude and longitude point set to draw route further. Can anybody get me the code to do so?
Thanks in advance

public class MapprojectActivity extends MapActivity {
/** Called when the activity is first created. */
static final String TAG_RESULTS = "results";
static final String TAG_GEO = "geometry";
static final String TAG_LOCATION = "location";
static final String TAG_LAT = "lat";
static final String TAG_LNG = "lng";
JSONArray res = null;
MapView mapView;
List<Overlay> mapOverlays;
Drawable drawable;
MyItemizedOverlay itemizedOverlay;
static String url = "http://maps.google.com/maps/api/geocode/json?address=guindy,+chennai,+IN&sensor=false";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.map);
TextView lattv=(TextView)findViewById(R.id.lat);
TextView lngtv=(TextView)findViewById(R.id.lng);
JSONParstring jParser = new JSONParstring();
// getting JSON string from URL
try
{
JSONObject jobj = new JSONObject(json);
res = jobj.getJSONArray(TAG_RESULTS);
for(int i = 0; i < res.length(); i++){
JSONObject c = res.getJSONObject(i);
JSONObject loc = c.optJSONObject(TAG_GEO).optJSONObject(TAG_LOCATION);
String lat =loc.getString(TAG_LAT);
String lng = loc.getString(TAG_LNG);
lattv.setText(lat);
lngtv.setText(lng);
}
}
catch (JSONException e){ }
String i=(String) lattv.getText();
String j=(String) lngtv.getText();
double lat1 = Double.parseDouble(i);
double lng1 = Double.parseDouble(j);
mapView = (MapView) findViewById(R.id.map_view);
mapView.setBuiltInZoomControls(false);
mapOverlays = mapView.getOverlays();
drawable = getResources().getDrawable(R.drawable.mark1);
itemizedOverlay = new MyItemizedOverlay(drawable, mapView);
GeoPoint point = new GeoPoint((int)(lat1*1E6),(int)(lng1*1E6));
OverlayItem overlayItem = new OverlayItem(point, "Amy Jones",
"(checked in Lemon-tree with friends lisa wong, paul jones)");
itemizedOverlay.addOverlay(overlayItem);
mapOverlays.add(itemizedOverlay);
final MapController mc = mapView.getController();
mc.animateTo(point);
mc.setZoom(16);
// Integer i = Integer.valueOf((String) lattv.getText());
// Integer j = Integer.valueOf((String) lngtv.getText());
// // first overlay
}
protected boolean isRouteDisplayed() {
return false;
}
}

Here is to get Latitude/Longitude from JSON http://blog.synyx.de/2010/06/routing-driving-directions-on-android-part-1-get-the-route/
And this is how to draw a route http://blog.synyx.de/2010/06/routing-driving-directions-on-android-%E2%80%93-part-2-draw-the-route/
u should study it. i hope it'll help.