Using Google Maps in Kotlin

Using Google Maps in Kotlin

Let’s explore how to integrate Google Maps and add markers in your Kotlin apps.

Project Setup

Dependencies

// build.gradle.kts
dependencies {
    implementation("com.google.android.gms:play-services-maps:18.2.0")
    implementation("com.google.android.gms:play-services-location:21.1.0")
}

API Key Setup

<!-- AndroidManifest.xml -->
<application>
    <meta-data
        android:name="com.google.android.geo.API_KEY"
        android:value="YOUR_API_KEY" />
</application>

Basic Map Integration

XML Layout

<!-- activity_main.xml -->
<fragment
    android:id="@+id/map"
    android:name="com.google.android.gms.maps.SupportMapFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

Map Initialization

class MainActivity : AppCompatActivity(), OnMapReadyCallback {
    private lateinit var map: GoogleMap

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val mapFragment = supportFragmentManager
            .findFragmentById(R.id.map) as SupportMapFragment
        mapFragment.getMapAsync(this)
    }

    override fun onMapReady(googleMap: GoogleMap) {
        map = googleMap

        // Set initial camera position
        val initialLocation = LatLng(-6.2088, 106.8456) // Jakarta
        map.moveCamera(CameraUpdateFactory.newLatLngZoom(initialLocation, 12f))

        // Enable user location
        map.isMyLocationEnabled = true

        // Enable zoom controls
        map.uiSettings.isZoomControlsEnabled = true
    }
}

Map Markers

Adding Markers

// Basic marker
val marker = map.addMarker(
    MarkerOptions()
        .position(LatLng(-6.2088, 106.8456))
        .title("Jakarta")
        .snippet("Capital of Indonesia")
)

// Custom marker
val customMarker = map.addMarker(
    MarkerOptions()
        .position(LatLng(-6.2088, 106.8456))
        .icon(BitmapDescriptorFactory.fromResource(R.drawable.custom_marker))
        .anchor(0.5f, 0.5f)
)

// Marker click listener
map.setOnMarkerClickListener { marker ->
    Toast.makeText(this, marker.title, Toast.LENGTH_SHORT).show()
    true
}

Map Controls

Camera Controls

// Camera movement
fun moveCamera(latLng: LatLng, zoom: Float = 15f) {
    map.animateCamera(
        CameraUpdateFactory.newLatLngZoom(latLng, zoom),
        1000,
        null
    )
}

// Camera bounds
fun fitBounds(locations: List<LatLng>) {
    val builder = LatLngBounds.builder()
    locations.forEach { builder.include(it) }
    map.animateCamera(
        CameraUpdateFactory.newLatLngBounds(builder.build(), 100),
        1000,
        null
    )
}

Location Services

Location Updates

class LocationManager(
    private val context: Context,
    private val lifecycleOwner: LifecycleOwner
) {
    private val fusedLocationClient = LocationServices.getFusedLocationProviderClient(context)
    private val locationRequest = LocationRequest.create().apply {
        priority = LocationRequest.PRIORITY_HIGH_ACCURACY
        interval = 10000
    }

    fun startLocationUpdates(callback: (Location) -> Unit) {
        if (ActivityCompat.checkSelfPermission(
                context,
                Manifest.permission.ACCESS_FINE_LOCATION
            ) == PackageManager.PERMISSION_GRANTED
        ) {
            fusedLocationClient.requestLocationUpdates(
                locationRequest,
                object : LocationCallback() {
                    override fun onLocationResult(locationResult: LocationResult) {
                        locationResult.lastLocation?.let { callback(it) }
                    }
                },
                Looper.getMainLooper()
            )
        }
    }
}

Custom Map Features

Custom Overlays

// Custom ground overlay
val groundOverlay = map.addGroundOverlay(
    GroundOverlayOptions()
        .position(LatLng(-6.2088, 106.8456), 1000f, 1000f)
        .image(BitmapDescriptorFactory.fromResource(R.drawable.overlay))
        .transparency(0.5f)
)

// Custom polyline
val polyline = map.addPolyline(
    PolylineOptions()
        .add(LatLng(-6.2088, 106.8456))
        .add(LatLng(-6.2188, 106.8556))
        .color(Color.RED)
        .width(5f)
)

Best Practices

Map State Management

// Save map state
override fun onSaveInstanceState(outState: Bundle) {
    super.onSaveInstanceState(outState)
    map?.let { googleMap ->
        outState.putParcelable("map_state", googleMap.cameraPosition)
    }
}

// Restore map state
override fun onRestoreInstanceState(savedInstanceState: Bundle) {
    super.onRestoreInstanceState(savedInstanceState)
    savedInstanceState.getParcelable<CameraPosition>("map_state")?.let { position ->
        map?.moveCamera(CameraUpdateFactory.newCameraPosition(position))
    }
}

Common Patterns

Map Utilities

// 1. Marker manager
class MarkerManager(private val map: GoogleMap) {
    private val markers = mutableMapOf<String, Marker>()

    fun addMarker(id: String, position: LatLng, title: String) {
        markers[id] = map.addMarker(
            MarkerOptions()
                .position(position)
                .title(title)
        )
    }

    fun removeMarker(id: String) {
        markers[id]?.remove()
        markers.remove(id)
    }

    fun updateMarker(id: String, position: LatLng) {
        markers[id]?.position = position
    }
}

// 2. Location tracker
class LocationTracker(
    private val context: Context,
    private val onLocationUpdate: (LatLng) -> Unit
) {
    private val locationManager = LocationManager(context, lifecycleOwner)

    fun startTracking() {
        locationManager.startLocationUpdates { location ->
            onLocationUpdate(LatLng(location.latitude, location.longitude))
        }
    }
}

Conclusion

Google Maps integration in Kotlin requires:

• Proper project setup
• Understanding map controls
• Managing markers
• Handling location updates
• Following best practices
• Using common patterns

Remember to:

• Handle permissions
• Manage map state
• Optimize performance
• Handle errors
• Test on different devices
• Follow Google Maps guidelines

Stay tuned for more Kotlin tips and tricks!