Building a Geocaching Application with Android’s Fused Location Library

Getting Started

Create a new Android Studio project and select Google Maps Activity as your template. Fill in your app name and package name, and then obtain an API key from the Google Console. Add the API key to your AndroidManifest.xml file.

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

Creating the Functionalities

Add the necessary dependencies to your build.gradle file:

dependencies {
    implementation 'com.google.android.gms:play-services-location:20.0.0'
    implementation 'com.google.android.gms:play-services-maps:18.0.2'
}

Set the required permissions in your AndroidManifest.xml file:

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

Creating Abstractions and Permission Settings

Create an interface file called ClientInfo.kt to abstract the location updates:

interface ClientInfo {
    fun getLocationUpdates(): Flow<Location>
}

Create a class file called DefaultClientInfo.kt to implement the interface:

class DefaultClientInfo(private val context: Context, private val fusedLocationProviderClient: FusedLocationProviderClient) : ClientInfo {
    override fun getLocationUpdates(): Flow<Location> {
        // Implement location updates logic here
    }
}

Foreground Service

Create a class file called LocServices.kt to create a foreground service:

class LocServices : Service() {
    companion object {
        const val START = "start"
    }

    override fun onStartCommand(intent: Intent, flags: Int, startId: Int): Int {
        // Start location updates here
        return super.onStartCommand(intent, flags, startId)
    }
}

Notification Channel

Create a class file called LocationApp.kt to create a notification channel:

class LocationApp : Application() {
    override fun onCreate() {
        super.onCreate()
        // Create notification channel here
    }
}

MapsActivity.kt

Modify the MapsActivity.kt file to handle the creation of a map with a marker:

class MapsActivity : AppCompatActivity(), OnMapReadyCallback {
    private lateinit var locationCallback: LocationCallback
    private lateinit var locationRequest: LocationRequest
    private lateinit var fusedLocationProviderClient: FusedLocationProviderClient

    override fun onMapReady(googleMap: GoogleMap) {
        // Create map with marker here
        launchIntent()
        getUpdatedLocation()
        startUpdate()
    }

    private fun launchIntent() {
        // Launch intent to start location updates
    }

    private fun getUpdatedLocation() {
        // Get updated location here
    }

    private fun startUpdate() {
        // Start location updates here
    }
}

Putting it all Together

Run your application, and you should see a map with a marker that continuously updates the user’s location. When the user is within a specific radius of the hidden item, they will receive a notification.