Android Jetpack Compose: How to Display Marker on Google Maps

We have seen Google Maps in many android applications. In this application to point to the specific location, a marker is used. In this article, we will take a look at How to display a marker on Google Maps in Android using Jetpack Compose. A sample video is given below to get an idea about what we are going to do in this article.

Step by Step Implementation

Step 1: Create a New Project in Android Studio

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. While choosing the template, select Empty Compose Activity. If you do not find this template, try upgrading the Android Studio to the latest version. We demonstrated the application in Kotlin, so make sure you select Kotlin as the primary language while creating a New Project.

Step 2: Adding a new color in the Color.kt file

Navigate to app > java > your app’s package name > ui.theme > Color.kt file and add the below code to it. 

Kotlin

package com.example.newcanaryproject.ui.theme

import androidx.compose.ui.graphics.Color

val Purple200 = Color(0xFF0F9D58)
val Purple500 = Color(0xFF0F9D58)
val Purple700 = Color(0xFF3700B3)
val Teal200 = Color(0xFF03DAC5)

// on below line we are adding different colors.
val greenColor = Color(0xFF0F9D58)

Step 3: Adding dependency to use Google Maps

Navigate to build.gradle file and add the below dependency in the build.gradle file.

implementation("com.google.android.libraries.maps:maps:3.1.0-beta")
implementation("com.google.maps.android:maps-v3-ktx:2.2.0")
implementation("androidx.fragment:fragment:1.3.2")

After adding the dependency simply click on the sync now option to install it.

Step 4: Adding permissions and google maps API key

Navigate to app>AndroidManifest.xml file and add the below code in the application tag for adding the API key. 

XML

<meta-data
  android:name="com.google.android.geo.API_KEY"
  android:value="Enter your API key" />

Check out the below article on How to generate API key for Google Maps in Android.

Step 5: Create a new layout file for the map layout

Navigate to app>res>Right click on it>New>Directory and name it as layout. Now right-click on that directory and click on New>Layout resource file. Create a new XML file and name it map_layout and add the below code to it. Comments are added in the code to get to know it in detail. 

XML

<?xml version="1.0" encoding="utf-8"?>
<androidx.fragment.app.FragmentContainerView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/map"
    android:name="com.google.android.gms.maps.SupportMapFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

Step 6: Create a new file for creating a Map

Navigate to app>java>your app’s package name>Right click on it>New>Kotlin class and name it as MapUtils and add the below code to it. Comments are added in the code to get to know it in detail. 

Kotlin

package com.example.newcanaryproject

import android.os.Bundle
import androidx.compose.runtime.Composable
import androidx.compose.runtime.DisposableEffect
import androidx.compose.runtime.remember
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.platform.LocalLifecycleOwner
import androidx.lifecycle.Lifecycle
import androidx.lifecycle.LifecycleEventObserver
import com.google.android.libraries.maps.MapView

// on below line creating a new
// composable widget for displaying map
@Composable
fun rememberMapViewWithLifecycle(): MapView {
    val context = LocalContext.current
    // on below line initializing
    // our maps view with id.
    val mapView = remember {
        MapView(context).apply {
            id = R.id.map
        }
    }

    // Makes MapView follow the lifecycle of this composable
    val lifecycleObserver = rememberMapLifecycleObserver(mapView)

    // on below line initializing lifecycle variable.
    val lifecycle = LocalLifecycleOwner.current.lifecycle

    // on below line adding observer for lifecycle.
    DisposableEffect(lifecycle) {
        lifecycle.addObserver(lifecycleObserver)
        onDispose {
            lifecycle.removeObserver(lifecycleObserver)
        }
    }
    // returning map view on below line.
    return mapView
}

@Composable
// creating a function for map lifecycle observer.
fun rememberMapLifecycleObserver(mapView: MapView): LifecycleEventObserver =
    remember(mapView) {
        // on below line adding different events for maps view
        LifecycleEventObserver { _, event ->
            when (event) {
                Lifecycle.Event.ON_CREATE -> mapView.onCreate(Bundle())
                Lifecycle.Event.ON_START -> mapView.onStart()
                Lifecycle.Event.ON_RESUME -> mapView.onResume()
                Lifecycle.Event.ON_PAUSE -> mapView.onPause()
                Lifecycle.Event.ON_STOP -> mapView.onStop()
                Lifecycle.Event.ON_DESTROY -> mapView.onDestroy()
                else -> throw IllegalStateException()
            }
        }
    }

Step 7: Working with the MainActivity.kt file

Go to the MainActivity.kt file and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail.

Kotlin

package com.example.newcanaryproject

import android.app.Activity
import android.content.*
import android.os.Bundle
import android.widget.Toast
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.*
import androidx.compose.material.*
import androidx.compose.runtime.Composable
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.text.TextStyle
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.text.style.TextAlign
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.compose.ui.viewinterop.AndroidView
import com.example.newcanaryproject.ui.theme.NewCanaryProjectTheme
import com.example.newcanaryproject.ui.theme.greenColor
import com.google.android.libraries.maps.CameraUpdateFactory
import com.google.android.libraries.maps.model.LatLng
import com.google.android.libraries.maps.model.MarkerOptions
import com.google.android.libraries.maps.model.PolylineOptions
import com.google.maps.android.ktx.awaitMap
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.launch
import java.io.FileInputStream
import java.io.FileOutputStream
import java.io.IOException

class MainActivity : ComponentActivity() {

    var message = ""
    override fun onCreate(savedInstanceState: Bundle?) {

        super.onCreate(savedInstanceState)
        setContent {
            NewCanaryProjectTheme {
                // on below line we are specifying background color for our application
                Surface(
                    // on below line we are specifying modifier and color for our app
                    modifier = Modifier.fillMaxSize(), color = MaterialTheme.colors.background
                ) {

                    // on the below line we are specifying the theme as the scaffold.
                    Scaffold(

                        // in scaffold we are specifying the top bar.
                        topBar = {

                            // inside top bar we are specifying background color.
                            TopAppBar(backgroundColor = greenColor,

                                // along with that we are
                                // specifying title for our top bar.
                                title = {

                                    // in the top bar we are
                                    // specifying title as a text
                                    Text(
                                        // on below line we are specifying
                                        // text to display in top app bar.
                                        text = "GFG",

                                        // on below line we are specifying
                                        // modifier to fill max width.
                                        modifier = Modifier.fillMaxWidth(),

                                        // on below line we are specifying
                                        // text alignment.
                                        textAlign = TextAlign.Center,

                                        // on below line we are specifying
                                        // color for our text.
                                        color = Color.White
                                    )
                                })
                        }) {
                        mapUI()
                        // on below line we are calling method to display UI
                    }
                }
            }
        }
    }
}

@Composable
fun mapUI() {
    val mapView = rememberMapViewWithLifecycle()

    // on below line creating a column for our maps.
    Column(
        modifier = Modifier
            .fillMaxHeight()
            .fillMaxWidth()
            .background(Color.White)
    ) {
        // on below line adding a map view to it.
        AndroidView({ mapView }) { mapView ->
            // on below line launching our map view
            CoroutineScope(Dispatchers.Main).launch {
                val map = mapView.awaitMap()
                // on below line adding zoom controls for map.
                map.uiSettings.isZoomControlsEnabled = true
                // on below line we are creating a lat lng
                // variable for sydney location
                val sydney = LatLng(-35.016, 143.321)
                // on below line adding a marker to map and
                // specifying tile and position for it.
                val markerOptions = MarkerOptions()
                    .title("Sydney")
                    .position(sydney)
                map.addMarker(markerOptions)
            }
        }
    }
}

Now run your application to see the output of it. 

Output: