I'm writing a Fragment that uses a loader to get a Cursor containing data about locations of various things on a map. I've inherited code to sort these locations by distance from the device, or from a search location; distance metrics aren't something that's particularly easy to implement in SQL, so rather than use a CursorAdapter (as elsewhere) I'm loading the data once from the Cursor and then sorting it afterwards.
I have just one problem: when the web service returns a new set of locations (for example, on first load), the list isn't updating. I've registered a ContentObserver on the Cursor and it is being hit when I call notifyChange(...) in the ContentProvider; it's just that the Cursor I've stored from the original load still has a count of zero.
The callbacks and the ContentObserver look like this:
private LoaderCallbacks<Cursor> mCallbacks = new LoaderCallbacks<Cursor>() {
public void onLoaderReset(Loader<Cursor> loader) {
mLoaderCreated = false;
mCursor.unregisterContentObserver(mObserver);
mCursor = null;
}
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
if(cursor!=mCursor) {
if(mCursor!=null)
mCursor.unregisterContentObserver(mObserver);
cursor.registerContentObserver(mObserver);
mCursor = cursor;
if(cursor.isClosed()) {
getLoaderManager().restartLoader(mFragmentId, null, mCallbacks);
return;
}
}
mDataModel.populate(cursor);
}
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
mLoaderCreated = true;
triggerServicesFeed();
CursorLoader cursorLoader = null;
if(id == mFragmentId) {
cursorLoader = new CursorLoader(getActivity(),
FerrariVertuContentProvider.SERVICES_URI,
null, null, null,null);
}
return cursorLoader;
}
};
private ContentObserver mObserver = new ContentObserver(null) {
public void onChange(boolean selfChange, android.net.Uri uri) {
onChange(selfChange);
};
public void onChange(boolean selfChange) {
if(mCursor.isClosed()) {
mCursor.unregisterContentObserver(this);
mCursor = null;
} else {
getActivity().runOnUiThread(new Runnable() {
#Override
public void run() {
//mCursor still reports zero on first run
mDataModel.populate(mCursor);
}
});
}
};
};
I know CursorAdapter just updates when the Cursor updates, and the fact that I'm getting update events when I'd expect to makes me think this stage of the process, at least, is working. How do I either get mCursor to give me the new data, or get a fresh Cursor representing the new data?
Related
I want to get the object count from 5 classes in Parse.com (to check if all objects were fetched successfully).
Because I'm using findObjectsInBackgroundWithBlock: sometimes not all the objects are fetched before I'm using it, that's why I want to check.
How can I do that?
Update 2: just noticed you were asking about iOS. its basically the same principle, use fetchAllIfNeeded like so:
https://parse.com/docs/ios/api/Categories/PFObject(Synchronous).html#/c:objc(cs)PFObject(cm)fetchAllIfNeeded:
Update: a better way than the naive one (below) would probably be using fetchAllIfNeededInBackground:
ArrayList<ParseObject> objectsToFetch = new ArrayList<>();
objectsToFetch.add(object1);
objectsToFetch.add(object2);
objectsToFetch.add(object3);
ParseObject.fetchAllIfNeededInBackground(objectsToFetch, new FindCallback<ParseObject>() {
#Override
public void done(List<ParseObject> objects, ParseException e) {
//all are fetched, do stuff
}
});
My native way of doing this is adding an outer boolean array where each boolean is responsible for one of the classes.
When a findObjectsInBackgroundWithBlock's 'done' function runs, I set that boolean to "true" and run a function that checks whether all array is true, if so -> all classes have been fetched and I can continue.
example from my code:
boolean[] itemFetched;
protected void getAllClassesAndDoStuffWithThem() {
itemFetched= new boolean[NUM_OF_CLASSES];
for (int i=0;i<NUM_OF_CLASSES;i++){
final int finalI = i;
itemFetched[i] = false;
parseObjectArray[i].fetchIfNeededInBackground(new GetCallback<ParseObject>() {
#Override
public void done(ParseObject object, ParseException e) {
itemFetched[finalI] = true;
finishInitIfPossible();
}
});
}
}
private void finishInitIfPossible() {
for (int i=0;i<NUM_OF_CLASSES;i++){
if (!itemFetched[i])
return;
}
//all classes fetched
finishInit();
}
private void finishInit() {
//do stuff with all 5 classes
}
i'm creating one application in which i get gift images with id's from web server through JSON. When i click on any gift image, it goes on next page where it shows all information of that image (get image information with its id from web server through JSON).
Problem is: When i click on any gift image on page to see its relevant information, it gets the last gift image id every time, i want when i click on any image, it gets the specific image id which i click. How it is possible??
Screenshot of the page is : http://ugo.offroadstudios.com/gifts.png
Here is sample code:
public class Gifts extends MainScreen {
String giftsid;
BitmapField giftimg;
public Gifts(){
setTitle("Gift Store");
creategifts();
}
public void creategifts()
{
//Link URL
String strURL = "http://ugo.offroadstudios.com/api/frndgift/?loginusername=adil;deviceside=true";
webConnection wb = new webConnection();
String res = wb.getJson(strURL);
try {
JSONObject object = new JSONObject(res);
if(object.getString("status") == "error")
{
Dialog.alert("Invalid "+object.getString("status"));
}
else
{
int totalgifts;
totalgifts = object.getInt("totalgifts");
Bitmap listThumb;
JSONArray imagearr;
JSONArray giftsidarr;
String imgname;
Bitmap bmpResized;
for(int i=0; i < totalgifts; i++){
imagearr = object.getJSONArray("gifts_image");
imgname = imagearr.getString(i);
giftsidarr = object.getJSONArray("gifts_id");
giftsid = giftsidarr.getString(i);
listThumb = getImage.getImageFromUrl("http://ugo.offroadstudios.com/wp-content/plugins/bp-gifts-rebirth/includes/images/"+imgname+";deviceside=true");
bmpResized = GPATools.ResizeTransparentBitmap(listThumb, 80, 80,
Bitmap.FILTER_LANCZOS, Bitmap.SCALE_TO_FIT);
giftimg =new BitmapField(bmpResized,FOCUSABLE)
{
protected boolean navigationClick(int status, int time)
{
Dialog.alert("giftsid "+giftsid);
UiApplication.getUiApplication().pushScreen(new SendGift(giftsid));
return true;
}
};
add(giftimg);
}
}
}
catch (JSONException e) {
System.out.println("EX is "+e);
e.printStackTrace();
}
}
}
You are always getting the gift id of the last gift in the list because you have created your buttons with this code:
giftimg =new BitmapField(bmpResized,FOCUSABLE)
{
protected boolean navigationClick(int status, int time)
{
Dialog.alert("giftsid "+giftsid);
UiApplication.getUiApplication().pushScreen(new SendGift(giftsid));
return true;
}
};
Your navigationClick() method used the giftsid variable, which is a persistent member variable of your class. You assign this variable in your for loop, so the final value it keeps is the last value assigned in the loop (giftsidarr.getString(totalgifts)).
Although you declare the navigationClick() method in a loop where the giftsid is many different values, the navigationClick() method uses the value of giftsid when it is run. The last value.
There's many ways to fix it. You can use a separate constant value in your loop:
final String nextGiftsId = giftsid;
giftimg =new BitmapField(bmpResized,FOCUSABLE)
{
protected boolean navigationClick(int status, int time)
{
Dialog.alert("nextGiftsId= "+nextGiftsId);
UiApplication.getUiApplication().pushScreen(new SendGift(nextGiftsId));
return true;
}
};
Or, as Signare suggested, attach a cookie to each button that identifies its corresponding gift:
giftimg =new BitmapField(bmpResized,FOCUSABLE)
{
protected boolean navigationClick(int status, int time)
{
String giftId = (String)getCookie(); // read gift id from the cookie
Dialog.alert("giftId= "+giftId);
UiApplication.getUiApplication().pushScreen(new SendGift(giftId));
return true;
}
};
giftimg.setCookie(giftsid); // set the cookie after creating the field
Inside your for loop, add the following code -
giftimg[i].setChangeListener(this);
Then -
public void fieldChanged(Field field, int context) {
for(int i=0;i<totalgifts;i++) {
if(field == giftimg[i]) {
// you can trigger your event
}
}
EDIT :-
giftimg[i].setChangeListener(listener);
listener = new FieldChangeListener() {
public void fieldChanged(Field field, int context) {
if ( field instanceof BitmapField ) {
for(int i=0;i<totalgifts;i++) {
if ( field == giftimg[i] ) {
// you can trigger your event
}
}
}
}
};
I am working on a BlackBerry Application that is supposed to update the location at fixed intervals. The interval value can be selected/changed from a slider. It varies between 1 minute, 2 minutes, 5 minutes, 30 minutes etc. On the very first load (Start App), location interval is 30 seconds. After this, I store the slider value in a persistent store and location is updated accordingly with the set interval. Background thread running to update location is as follows:
private boolean startLocationUpdate()
{
boolean retval = false;
try
{
LocationProvider locationProvider = LocationProvider.getInstance(null);
if ( locationProvider == null )
{
Runnable showGpsUnsupportedDialog = new Runnable()
{
public void run()
{
Dialog.alert("GPS is not supported on this platform, exiting...");
//System.exit( 1 );
}
};
UiApplication.getUiApplication().invokeAndWait( showGpsUnsupportedDialog ); // Ask event-dispatcher thread to display dialog ASAP.
}
else
{
locationProvider.setLocationListener(new LocationListenerImpl(), interval, -1, -1);
retval = true;
}
}
catch (LocationException le)
{
System.err.println("Failed to instantiate the LocationProvider object, exiting...");
System.err.println(le);
System.exit(0);
}
return retval;
}
private class LocationListenerImpl implements LocationListener
{
public void locationUpdated(LocationProvider provider, Location location)
{
if(location.isValid())
{
double longitude = location.getQualifiedCoordinates().getLongitude();
double latitude = location.getQualifiedCoordinates().getLatitude();
updateLocationScreen(latitude, longitude);
}
}
public void providerStateChanged(LocationProvider provider, int newState)
{
}
}
private void updateLocationScreen(final double latitude, final double longitude)
{
UiApplication.getUiApplication().invokeAndWait(new Runnable()
{
public void run()
{
double lat = latitude;
double longi = longitude;
lblLatitude.setText(Double.toString(lat));
spacing.setText(", ");
lblLongitude.setText(Double.toString(longi));
}
});
}
Along with this, there is a "Refresh" button available that will start acquiring a location update immediately once clicked. This button calls a method is another class to acquire the location. The method is as follows:
try {
Criteria myCriteria = new Criteria();
myCriteria.setCostAllowed(false);
LocationProvider myLocationProvider = LocationProvider.getInstance(myCriteria);
double heading = 0;
double velocity = 0;
try {
Location myLocation = myLocationProvider.getLocation(6000);
if(myLocation.isValid())
{
double longitude = myLocation.getQualifiedCoordinates().getLongitude();
double latitude = myLocation.getQualifiedCoordinates().getLatitude();
}
UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run() {
//Dialog.alert("Location Updated");
}
});
setLocation(myLocation.getQualifiedCoordinates(),velocity,heading);
} catch ( InterruptedException iex ) {
System.out.println(iex.getMessage());
} catch ( LocationException lex ) {
System.out.println(lex.getMessage());
}
} catch ( LocationException lex ) {
System.out.println(lex.getMessage());
}
Problems I am facing:
1) Interval value not changing. I am implementing the change by picking the value from the persistent store as:
if (PersistentStoreHelper.persistentHashtable.containsKey("gpsInterval"))
{
String intervalValue=((String) PersistentStoreHelper.persistentHashtable.get("gpsInterval"));
MyScreen.interval=Integer.parseInt(intervalValue);
}
This is never empty as navigation to this page inserts a value of 30 minutes to it.
2) Once the "Refresh" button is clicked, the background thread seems to be cancelled. It no longer runs at any interval value.
I read that there is only one instance of the location provider created and with "Refresh" it is cancelled after acquiring the location and thus the background thread stops. Is this true? If yes, how can I achieve my desired result.
EDIT: The gpsInterval value is read as follows:
if (PersistentStoreHelper.persistentHashtable.containsKey("gpsInterval"))
{
String intervalValue=((String)PersistentStoreHelper.persistentHashtable.get("gpsInterval"));
interval=Integer.parseInt(intervalValue);
}
else
{
interval=10;
}
Saving the Interval
So, first of all, make sure that when you let the user change the update interval, via the slider, you properly save it to the PersistentStore. The code should look something like this:
// NOTE: I would recommend persisting the slider value as an Integer, not a String,
// but, the original code used String, so that's what this uses
hashtable.put("gpsInterval", (new Integer(intervalSlider.getValue())).toString());
PersistentObject po = PersistentStore.getPersistentObject(APP_BUNDLE_ID);
po.setContents(hashtable);
po.commit();
Since you didn't post that code, I just wanted to be sure that it was being saved to the persistent store correctly.
Updating the Location Provider / Listener
The other issue, that is a problem, is that you kick off the location updates in startLocationUpdate() with this code:
locationProvider.setLocationListener(new LocationListenerImpl(), interval, -1, -1);
That uses the value of the interval variable at the instant that setLocationListener() is called. If you later update the interval variable,
String intervalValue=((String) PersistentStoreHelper.persistentHashtable.get("gpsInterval"));
MyScreen.interval=Integer.parseInt(intervalValue);
this will have no effect on the location listener. It will keep updating with the original interval value, not the new one. You would have to call setLocationListener() again, with the new value of interval. With your code, you should probably just call startLocationUpdate() again:
String intervalValue=((String) PersistentStoreHelper.persistentHashtable.get("gpsInterval"));
MyScreen.interval=Integer.parseInt(intervalValue);
startLocationUpdate();
Refresh Problem
I'm not 100% sure, but my guess would be that in your existing code that's used when the Refresh button is pressed, you are changing to a different LocationProvider with different criteria. That's probably why the first one is cancelled.
Try changing your startLocationUpdate() method to save the provider as a member variable:
/** this is the one location provider used by this class! */
private LocationProvider _locationProvider;
private boolean startLocationUpdate()
{
boolean retval = false;
try
{
_locationProvider = LocationProvider.getInstance(null);
then, in your refresh code, use the same location provider to get the current location:
double heading = 0;
double velocity = 0;
try {
Location myLocation = _locationProvider.getLocation(6000);
if(myLocation.isValid())
Note: if you really do want to setCostAllowed(false), that's fine. Do that the first time that you assign the _locationProvider member variable. And use that provider/criteria both for normal periodic location updates, and your Refresh button handler. I think the key is to use the same provider, not create a new one with different criteria.
I'm rolling my own ActivatableCollection<T> for db4o but cribbing heavily from the builtin ActivatableList<T> implementation. I'm running into the problem where transparent persistence doesn't seem to be working correctly. In the test code below:
[Fact]
void CanStoreActivatableCollection()
{
var planets = new ActivatableCollection<Planet>();
var pagingMemoryStorage = new PagingMemoryStorage();
var config = Db4oEmbedded.NewConfiguration();
config.Common.Add(new TransparentActivationSupport());
config.Common.Add(new TransparentPersistenceSupport());
config.File.Storage = pagingMemoryStorage;
var objectContainer = Db4oEmbedded.OpenFile(config, "Memory.yap");
planets.Add(new Planet("Mercury"));
objectContainer.Store(planets);
planets.Add(new Planet("Venus"));
planets.Add(new Planet("Earth"));
objectContainer.Commit();
objectContainer.Close();
config = Db4oEmbedded.NewConfiguration();
config.Common.Add(new TransparentActivationSupport());
config.Common.Add(new TransparentPersistenceSupport());
config.File.Storage = pagingMemoryStorage;
objectContainer = Db4oEmbedded.OpenFile(config, "Memory.yap");
planets = objectContainer.Query<ActivatableCollection<Planet>>().FirstOrDefault();
Assert.NotNull(planets);
Assert.Equal(3, planets.Count);
objectContainer.Close();
}
The planet "Mercury" is stored, but not "Venus" and "Earth". If I change from ActivatableCollection to ActivatableList, then all 3 planets are stored.
What am I missing? My ActivatableCollection is just minimal implementation of ActivatableList as best as I can tell.
Below is my implementation of ActivatableCollection:
public class ActivatableCollection<T>
: ICollection<T>
, IActivatable
, INotifyCollectionChanged
{
List<T> _list;
List<T> List
{
get
{
if (_list == null)
_list = new List<T>();
return _list;
}
}
public ActivatableCollection()
{
}
public int Count
{
get
{
ActivateForRead();
return List.Count;
}
}
public bool IsReadOnly
{
get
{
ActivateForRead();
return ((IList) List).IsReadOnly;
}
}
public void Add(T t)
{
ActivateForWrite();
List.Add(t);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, t));
}
public void Clear()
{
ActivateForWrite();
List.Clear();
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
public bool Contains(T t)
{
ActivateForRead();
return List.Contains(t);
}
public void CopyTo(T[] array, int index)
{
ActivateForRead();
List.CopyTo(array, index);
}
public IEnumerator<T> GetEnumerator()
{
ActivateForRead();
return List.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
public bool Remove(T t)
{
ActivateForWrite();
bool removed = List.Remove(t);
if (removed)
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, t));
return removed;
}
[Transient]
private IActivator _activator;
public virtual void Bind(IActivator activator)
{
if (_activator == activator)
return;
if (activator != null && _activator != null)
throw new InvalidOperationException();
_activator = activator;
}
public virtual void Activate(ActivationPurpose purpose)
{
if (_activator == null)
return;
_activator.Activate(purpose);
}
protected virtual void ActivateForRead()
{
Activate(ActivationPurpose.Read);
}
protected virtual void ActivateForWrite()
{
Activate(ActivationPurpose.Write);
}
[Transient]
public event NotifyCollectionChangedEventHandler CollectionChanged;
protected virtual void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
{
if (CollectionChanged != null)
CollectionChanged(this, e);
}
}
I've also tried copying the code from GenericTypeHandlerPredicate and registering my ActivatableCollection to use the GenericCollectionTypeHandler. That results in a crash in GenericTypeFor() throwing an InvalidOperationException() when "Mercury" is being stored.
Just want to mention my answers from the db4o forums also here, for people with a similar problem:
First part of the issue:
From db4o's point of view nothing has changed in the 'ActivatableCollection' object and therefore no changes are stored. This is what is happening:
When you add the items, the ActivatableCollection is marked as changed.
When you commit the changes are stored. However the ' ActivatableCollection' holds the reference to the same object. db4o only stores the changes in the ActivatableCollection-object, which is the reference to the List. Since it is the same, no actual change is stored.
The List of the ActivatableCollection is never updated, because it wasn't marked as 'changed'
So the transparent activation doesn't see the changes in the list. You can fix your issue simply by using an ActivatableList in you're ActivatableCollection implementation. Just change the List with a IList interface and instantiate a ActivatableList instead of an List.
The second part of the issue: Why doesn't it work even when registering the GenericCollectionTypeHandler for this type? Here we hit a implementation detail. The GenericCollectionTypeHandler has an internal list of supported types, which doesn't include the self made 'ActivatableCollection'. GenericCollectionTypeHandler is not really part of the public API and intendet for internal use only.
Workaround / Fix
Just use an ActivatableList<T> instead of a List<T>. then everything works fine.
I have a BlackBerry application that needs to take pictures from the camera and send them to a server. In order to do this i invoke the native camera application and listen to the filesystem. Once an image is captured and saved as a new jpeg file i get notified, resume foreground control and go about my business. The problem starts occurring after the first time this cycle is completed because now when i decide to call the camera application again it is already opened, and now the user is seeing a thumbnail of the last picture that was taken and several buttons allowing him to manipulate/manage it. naturally what i want the user to see is a preview of what the camera is "seeing" before he snaps another photo as he did before.
I have thought of various ways to solve this including killing the camera app each time (I understand this cannot be done programatically?), sending CameraArguments when invoking the app (which appears to be useless), and now i was thinking a solution could be as simple generating a "Back" key event before switching back to my app which would theoretically dismiss the annoying edit screen. Could this really be done? and if not is there any other possible solution you may think of?
A kind of hack...
start Camera App
in TimerTask check if Camera App started and if it need to be closed (some flag)
if yes, invoke it(so it will became active) and push ESC keypress event injection to close it
Take a look at this:
class Scr extends MainScreen {
boolean killCameraApp = false;
final String mCameraModuleName = "net_rim_bb_camera";
final CameraArguments args = new CameraArguments();
public Scr() {
super();
Timer timer = new Timer();
timer.scheduleAtFixedRate(new TimerTask() {
public void run() {
if (isCameraRunning() && killCameraApp) {
getApplication().invokeAndWait(callCamera);
getApplication().invokeAndWait(killCamera);
}
}
}, 0, 100);
}
Runnable callCamera = new Runnable() {
public void run() {
callCamera();
}
};
Runnable killCamera = new Runnable() {
public void run() {
injectKey(Characters.ESCAPE);
killCameraApp = false;
}
};
private boolean isCameraRunning() {
boolean result = false;
ApplicationManager appMan =
ApplicationManager.getApplicationManager();
ApplicationDescriptor[] appDes = appMan.getVisibleApplications();
for (int i = 0; i < appDes.length; i++) {
result = mCameraModuleName.equalsIgnoreCase(appDes[i]
.getModuleName());
if (result)
break;
}
return result;
}
private void callCamera() {
Invoke.invokeApplication(Invoke.APP_TYPE_CAMERA,
new CameraArguments());
}
private void injectKey(char key) {
KeyEvent inject = new KeyEvent(KeyEvent.KEY_DOWN, key, 0);
inject.post();
}
protected void makeMenu(Menu menu, int instance) {
menu.add(new MenuItem("start camera", 0, 0) {
public void run() {
callCamera();
killCameraApp = false;
}
});
menu.add(new MenuItem("kill app", 0, 0) {
public void run() {
killCameraApp = true;
}
});
super.makeMenu(menu, instance);
}
}
EDIT: Don't forget to set permissions for device release:
Options => Advanced Options => Applications => [Your Application] =>Edit Default permissions =>Interactions =>key stroke Injection