Internet connection check using LiveData. For android version M or higher.

InternetConnectionCheck.kt

class InternetConnectionCheck (context: Context) : LiveData<Boolean>() {

    private val connectivityManager = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager

    override fun onActive() {
        super.onActive()
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            connectivityManager.registerDefaultNetworkCallback(getNetworkCallback())
        } else {
            connectivityManager.registerNetworkCallback(getNetworkRequest(), getNetworkCallback())
        }
    }

    override fun onInactive() {
        super.onInactive()
        try {
            connectivityManager.unregisterNetworkCallback(getNetworkCallback())
        } catch (e: Exception) {
            e.printStackTrace()
        }
    }

    private fun getNetworkCallback() = object : ConnectivityManager.NetworkCallback() {

        override fun onAvailable(network: Network) {
            super.onAvailable(network)
            postValue(true)
        }

        override fun onLost(network: Network) {
            super.onLost(network)
            postValue(false)
        }
    }

    private fun getNetworkRequest() = NetworkRequest.Builder()
            .addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
            .addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR)
            .addTransportType(NetworkCapabilities.TRANSPORT_ETHERNET)
            .addCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)
            .build()
}

MainActivity.kt

class MainActivity : AppCompatActivity() {

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

        InternetConnectionCheck(this).observe(this, Observer { isConnected ->
            if (isConnected) {
                // do something
            }
        })
      
    }
}

MyApplication.kt

class MyApplication : Application() {

    override fun onCreate() {
        super.onCreate()

        InternetConnectionCheck(this).observeForever({ isConnected ->
            if (isConnected) {
                // do something
            }
        })
    }
}