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Question

I'm stuck on limiting the number of marker that user can tapped on the Google Map's map

The problem: Whenever the user tap on google map the marker keeps creating new ones and the old ones does not clear away.

Update: I think that it does not fall into the else if statement. Because every time the function is called it restart the process. Thus allowing the marker to be create constantly.

override fun onMapClick(point: LatLng){

val tappedLocation = LatLng(latitude,longitude)
        var mapMarkerCount: Int =0

        if(mapMarkerCount == 0) {
            map.addMarker(
                    MarkerOptions()
                            .position(tappedLocation)
                            .title("You have Clicked")

            )
            
            mapMarkerCount++

        }//check Marker Count
        else if(mapMarkerCount == 1){

            map.clear()
            mapMarkerCount--
        }
}

What I have tried is assigning a variable to sort of check the whether the marker has been created. and if the marker exists, upon the next tap on the map it is supposed to clear the map and the new marker is at the new location that the user has tapped.

Answer 1

I apologize for my bad English in advance

i think that your problem comes from your variable declaration.

you should try to : delete the mapMarkerCount=0 and make it boolean i think that the program execute mapMarkerCount=0 everytime you add a marker so i my mind it explain why you can't delete the old one

if (markerExist == false)
addOne();
markerExist=true;
elsif (markerExist == true)
map.clear();
add one();

with this code, the first time you will only add a new marker. and after you will clear the old marker and put the new one each time you touch the screen

Answer 2

Since override fun onMapClick(point: LatLng) ,

meaning to say that whenever the function is called it will always execute line by line of the fun onMapClick .

What you can do is, you can use map.clear() before placing maps.addMarker() So whenever the function is called it will clear the map first before adding.

override fun onMapClick(point: LatLng){

map.clear() //above the adding of marker

val tappedLocation = LatLng(latitude,longitude)

map.addMarker(
                    MarkerOptions()
                            .position(tappedLocation)
                            .title("You have Clicked")

            )
}

Essentially you do not need make a marker for check. Not recommended if you have you want to keep multiple markers or other stuff as it will wipe out anything on the google map. To the default map when user first see.

Answer 3

What your code is assign mapMarkerCount = 0 on every time the map is clicked, even though there might be a marker already on the map. And because of that it will always fall into the if statement block, because mapMarkerCount will never be equal to 1 when the map is clicked. Doing this assignment at the very beginning of onCreate would be a better option. Or as someone here has suggested, a boolean variable should be fine for your purpose considering you only wish to have one marker on the map. One implementation:

var mapMarkerExists: Boolean = false

override fun onMapClick(point: LatLng) {

    val tappedLocation = LatLng(latitude,longitude)

    if(mapMarkerExists) {
        map.clear()
        map.addMarker(
            MarkerOptions()
                .position(tappedLocation)
                .title("You have Clicked"))
    }//check Marker Count
    else {
        map.addMarker(
            MarkerOptions()
                .position(tappedLocation)
                .title("You have Clicked"))
        mapMarkerExists = true
    }
}