Snippet for fetching contacts in Android

get-contacts-android.kt

// Declare the data class in Contact.kt
data class Contact(
    val id: String,
    val name: String,
    val thumbnailUri: String?
)

// Following code goes into Fragment or Activity file
// This snippet is used in Android Fragments. Change it accordingly for using it in Activities

// Declare in Global scope before class declaration
private val PROJECTION: Array<out String> = arrayOf(
    ContactsContract.Contacts._ID,
    ContactsContract.Contacts.LOOKUP_KEY,
    ContactsContract.Contacts.PHOTO_THUMBNAIL_URI,
    ContactsContract.Contacts.DISPLAY_NAME_PRIMARY
)

class .... : Fragment(), CoroutineScope {
  
  // Global params
  // Coroutine
  private lateinit var mJob: Job
  override val coroutineContext: CoroutineContext
      get() = mJob + Dispatchers.Main
  
  override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)

    // Launch Coroutine to retrieve Contacts
    mJob = Job()
    launch {

        val contacts: ArrayList<Contact> = ArrayList()

        // Switch context to run on Background Thread
        val deferred = async(Dispatchers.Default) {

            val cursor = getContacts()

            cursor?.let {
                if (cursor.count > 0) {
                    while (cursor.moveToNext()) {

                        val id = cursor.getString(
                            cursor.getColumnIndex(ContactsContract.Contacts._ID)
                        )

                        var name = cursor.getString(
                            cursor.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME_PRIMARY)
                        )
                        if (name == null) {
                            name = "Unknown"
                        }

                        val thumbUri = cursor.getString(
                            cursor.getColumnIndex(ContactsContract.Contacts.PHOTO_THUMBNAIL_URI)
                        )

                        contacts.add(Contact(id, name, thumbUri))

                    }
                }
            }

        }

        deferred.await()
        
        // Contacts are saved in contacts array
        // For eg: setupContactsAdapter(contacts)

     }
  }

  /**
  * Use Content Resolver to retrieve contacts
  */
  private fun getContacts(): Cursor? {
    
    val contentResolver = activity?.contentResolver
    
    contentResolver?.let {
        return it.query(
            ContactsContract.Contacts.CONTENT_URI,
            PROJECTION,
            null,
            null,
            ContactsContract.Contacts.DISPLAY_NAME_PRIMARY
        )
    }
    return null
  }
  
}