Clustering markers on Android 10 with Kotlin

Question

I have found that there's mostly just Java code examples on Google's development site, and very few in Kotlin too which is pretty annoying so I have to ask this here.

I'm trying to setup a ClusterManager, but i don't have any clues how it's supposed to be done, and there's no Kotlin examples to be seen. I did manage this much:

override fun onMapReady(googleMap: GoogleMap) {
    // return early if the map was not initialised properly
    mMap = googleMap ?: return


    with(mMap.uiSettings) {
        isZoomControlsEnabled = true
        isMyLocationButtonEnabled = true
        isCompassEnabled = true
        isRotateGesturesEnabled = true
        isZoomGesturesEnabled = true
    }

    val clusterManager = ClusterManager<ScootMarker>(this, mMap)
    mMap.setOnCameraIdleListener(clusterManager)
    mMap.setOnMarkerClickListener(clusterManager)
    mMap.setOnInfoWindowClickListener(clusterManager)
    mMap.setInfoWindowAdapter(CustomInfoWindowAdapter(this))
    mMap.mapType = GoogleMap.MAP_TYPE_HYBRID

    setUpMap()
    getData()
}

I however don't know how I'm supposed to add markers to that ClusterManager, nor how to bind it to my CustomInfoWindowAdapter.

I already have my own custom item done, which returns the snippet, location and title.

Answer 1

Please try the code below for guidance and demonstration of how to add a marker clusterer in Kotlin.

class MyItem : ClusterItem {
    private val mPosition: LatLng
    private val mTitle: String
    private val mSnippet: String

    constructor(lat: Double, lng: Double) {
        mPosition = LatLng(lat, lng)
        mTitle = ""
        mSnippet = ""
    }

    constructor(lat: Double, lng: Double, title: String, snippet: String) {
        mPosition = LatLng(lat, lng)
        mTitle = title
        mSnippet = snippet
    }

    override fun getPosition(): LatLng {
        return mPosition
    }

    override fun getTitle(): String {
        return mTitle
    }

    override fun getSnippet(): String {
        return mSnippet
    }
}

class MapsActivity : AppCompatActivity(), OnMapReadyCallback, GoogleMap.OnInfoWindowClickListener {

    private lateinit var mMap: GoogleMap
    private lateinit var mClusterManager: ClusterManager<MyItem>

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_maps)
        val mapFragment = supportFragmentManager
            .findFragmentById(R.id.map) as SupportMapFragment
        mapFragment.getMapAsync(this)
    }

    override fun onMapReady(googleMap: GoogleMap) {
        mMap = googleMap
        setUpClusterer()
        mMap.setOnInfoWindowClickListener(this);
    }

    private fun setUpClusterer() {
        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(LatLng(51.503186, -0.126446), 10f))
        mClusterManager = ClusterManager(this, mMap)
        mMap.setOnCameraIdleListener(mClusterManager)
        mMap.setOnMarkerClickListener(mClusterManager)
        addItems()
    }

    private fun addItems() {
        var lat = 51.5145160
        var lng = -0.1270060
        for (i in 0..9) {
            val offset = i / 60.0
            lat = lat + offset
            lng = lng + offset
            val title = "This is the title"
            val snippet = "and this is the snippet."
            val offsetItem = MyItem(lat, lng, title, snippet)
            mClusterManager.addItem(offsetItem)
        }
    }

    override fun onInfoWindowClick(marker: Marker) {
        Toast.makeText(
            this, "Info window clicked",
            Toast.LENGTH_SHORT
        ).show()
    }
}

Note that this is based on the Java code implementation from Google's guides [1] [2] and it works without problem for me, so I hope this helps you!

[1] https://developers.google.com/maps/documentation/android-sdk/utility/marker-clustering
[2] https://developers.google.com/maps/documentation/android-sdk/infowindows