当 android 中的 Internet 连接丢失时通知用户

Question

I am trying to make an app where I need to notify the user via a toast when the connection to the internet is lost(either mobile data or wifi) and possibly launch another activity and return back to the main activity as soon as the user is back online. Can someone please guide me in doing this. Thank you.

Answer 1

You can use this to check if network is available

   public static boolean isNetworkAvailable(Context activity) {
    ConnectivityManager connectivityManager
            = (ConnectivityManager) activity.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
    return activeNetworkInfo != null && activeNetworkInfo.isConnected();
}

Use the above method as

  if(isNetworkAvailable(context)){
     //Network is available}
  else {
     //Network Unavailable
  }

Answer 2

Use NetworRequestCallBack provided by the Android to get the Internet connection changes. https://developer.android.com/reference/android/net/ConnectivityManager.NetworkCallback

    val connectivityManager = getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
    val networkRequest = NetworkRequest.Builder().build()
    connectivityManager.registerNetworkCallback(networkRequest, object :
        ConnectivityManager.NetworkCallback() {

        override fun onAvailable(network: Network) {
            super.onAvailable(network)
            // "Net connected"
        }

        override fun onLost(network: Network) {
            super.onLost(network)
            // "Network lost"
        }


        
    })

Answer 3

The behaviour you want to achieve can be achieved seamlessly using Reactive Network library. If you already use RxJava in your project then it is even more convenient!

Here it is documented how you can observe network connectivity https://github.com/pwittchen/ReactiveNetwork#observing-network-connectivity