Move all the markers on the map to their updated/new current location periodically as users moves

Question

I'm developing an android app where some users opens the same activity from their devices. There is a map in this activity and as users opens this activity from their devices, their location coordinates is fetched from Firebase and a marker based on these coordinates is shown on the map.

Here's my code:

acceptingUserReference.child(requestID).child(key).addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {

        if (dataSnapshot.getValue() != null) {
            final Map<String, String> newAcceptedUser = (Map<String, String>) dataSnapshot.getValue();
            
            nameOfP.add(newAcceptedUser.get("pName"));                      
            cLatP.add(newAcceptedUser.get("currentLat").trim());
            cLngP.add(newAcceptedUser.get("currentLng").trim());

            addMarkers();

            //Check map is loaded
            mMap.setOnMapLoadedCallback(new GoogleMap.OnMapLoadedCallback() {
                @Override
                public void onMapLoaded() {
                    mMap.getUiSettings().setZoomControlsEnabled(true);
                    mMap.getUiSettings().setMapToolbarEnabled(true);
                    mMap.setMapType(GoogleMap.MAP_TYPE_SATELLITE);
                    mMap.setMaxZoomPreference(19.0f);  mMap.setMyLocationEnabled(true);

                }
            });
            
            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });
    }
}

Here's addMarkers() method:

public void addMarkers() {
    mMap.clear();
    venueMarker = mMap.addMarker(new MarkerOptions().position(new LatLng(Double.parseDouble(venueLat), Double.parseDouble(venueLng)));
    markersList.add(venueMarker);
    for (int i = 0; i < nameOfP.size(); i++) {
        p = mMap.addMarker(new MarkerOptions().position(new LatLng(Double.valueOf(cLatP.get(i)), Double.valueOf(cLngP.get(i)))).title(nameOfP.get(i).trim()).icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED)));
        markersList.add(pMarker);
    }
}

Here's onLocationChanged():

@Override
public void onLocationChanged(Location location) {
    mCurrentLocation = location;
    currentLtAU = mCurrentLocation.getLatitude();
    currentLnAU = mCurrentLocation.getLongitude();
}

The users keeps moving towards a specific location.

What I want is to move the respective markers to the new location as the users moves so that everybody can see where each and everyone currently is. Please help me figure it out.

What is pMarker? isn't the variable you are assigning you marker to just p? Also, are you getting any errors, or is it just not working? — Nathan Bird, Feb 15 '17 at 20:57
I would suggest adding your markers to a `hashmap` based on the users "id" then edit the markers themselves as your app receives the values from Firebase rather than creating new ones every time. — Nathan Bird, Feb 15 '17 at 21:05
Call `acceptingUserReference.child(requestID)` whenever `onLocationChanged()` and update your location to `FireBase` — Kishore Jethava, Feb 22 '17 at 05:37
@KishoreJethava got the part till onLocationChanged(), please describe the part ahead. — Hammad Nasir, Feb 22 '17 at 06:17
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/136308/discussion-between-kishore-jethava-and-hammad-nasir). — Kishore Jethava, Feb 22 '17 at 06:42

score 0 · Answer 1 · edited Feb 15 '17 at 21:47

0

Save the result of addMarker and later call setPosition on it (result of addMarker).

edited Feb 15 '17 at 21:47

Moinuddin Quadri

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answered Feb 15 '17 at 21:04

danny117

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score 0 · Answer 2 · answered Feb 16 '17 at 14:58

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It appears as if there is nothing wrong with your code. I am sorry I could not find anything wrong with it as it is, but here is a file that you can use as a guideline to find the problem:

http://pastebin.com/9qq484Fz

I hope you solve the problem soon! (Apologies for the messy code, it's pretty old)

answered Feb 16 '17 at 14:58

Nathan Bird

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thanks for the code, buddy. have you find the other way of doing this as you asked here: http://stackoverflow.com/q/39778805/6144372 – Hammad Nasir Feb 18 '17 at 19:28
and what is `mFriends`? – Hammad Nasir Feb 19 '17 at 01:24
@hammadnasir the friendlist and mFriends variables are just lists of friend IDs... Not crucial to the rest of the code. – Nathan Bird Feb 19 '17 at 20:45
`friendList` is being used in `onStart`. From where are you populating it? Please tell me, – Hammad Nasir Feb 21 '17 at 06:41
@HammadNasir I'm using friendList to store the Google Play Games Ids of my "friends" I populate it when someone adds a friend. I forgot to remove that from the Pastebin but because it was a guest account I can't change it. – Nathan Bird Feb 22 '17 at 15:07

score 0 · Answer 3 · edited May 23 '17 at 10:29

0

1. Whenever onLocationChanged called means user moved to some distance.

Update user's updated location on Firebase in onLocationChanged so, other user can find your updated location.

Note: use geofire to update user location and see this answer.

@Override
public void onLocationChanged(Location location) {
mCurrentLocation = location;
currentLtAU = mCurrentLocation.getLatitude();
currentLnAU = mCurrentLocation.getLongitude();
}

2. call acceptingUserReference.child(requestID) code when you successfully update user location to Firebase

edited May 23 '17 at 10:29

Community

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answered Feb 22 '17 at 06:40

Kishore Jethava

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is it what your are asking? – Kishore Jethava Feb 22 '17 at 16:19
was working on another problem... sorry for replying so late... instead of GeoFIre can I just save keep saving the updated location (whenever the location changes) along with user's other data and then keep calling `acceptingUserReference.child(requestID)` from within `onLocationChanged()`?. – Hammad Nasir Feb 22 '17 at 19:54
I'm unable to do this... it's just not happening, bro. Isn't there any other way? – Hammad Nasir Feb 24 '17 at 02:51
what not happening? – Kishore Jethava Feb 24 '17 at 04:45
whenever I'm trying to fetch updated location in an array, the array gets filled with many items and I gets arrayoutofboundsexception and also many markers are shown on map... something weird is happening. isn't there a simpler way? – Hammad Nasir Feb 24 '17 at 04:53
have you checked it out?? – Hammad Nasir Feb 24 '17 at 08:32

Move all the markers on the map to their updated/new current location periodically as users moves

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