I got a AsyncTask
that is supposed to check the network access to a host name. But the doInBackground()
is never timed out. Anyone have a clue?
Im using this code instead of the InetAddress :
try {
URL url = new URL("http://"+params[0]);
HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
urlc.setRequestProperty("User-Agent", "Android Application:"+Z.APP_VERSION);
urlc.setRequestProperty("Connection", "close");
urlc.setConnectTimeout(1000 * 30); // mTimeout is in seconds
urlc.connect();
if (urlc.getResponseCode() == 200) {
Main.Log("getResponseCode == 200");
return new Boolean(true);
}
} catch (MalformedURLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Just create the following class which checks for an internet connection:
public class ConnectionStatus {
private Context _context;
public ConnectionStatus(Context context) {
this._context = context;
}
public boolean isConnectionAvailable() {
ConnectivityManager connectivity = (ConnectivityManager) _context
.getSystemService(Context.CONNECTIVITY_SERVICE);
if (connectivity != null) {
NetworkInfo[] info = connectivity.getAllNetworkInfo();
if (info != null)
for (int i = 0; i < info.length; i++)
if (info[i].getState() == NetworkInfo.State.CONNECTED) {
return true;
}
}
return false;
}
}
This class simply contains a method which returns the boolean value of the connection status. Therefore in simple terms, if the method finds a valid connection to the Internet, the return value is true
, otherwise false
if no valid connection is found.
The following method in the MainActivity then calls the result from the method previously described, and prompts the user to act accordingly:
public void addListenerOnWifiButton() {
Button btnWifi = (Button)findViewById(R.id.btnWifi);
iia = new ConnectionStatus(getApplicationContext());
isConnected = iia.isConnectionAvailable();
if (!isConnected) {
btnWifi.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(Settings.ACTION_WIFI_SETTINGS));
Toast.makeText(getBaseContext(), "Please connect to a hotspot",
Toast.LENGTH_SHORT).show();
}
});
}
else {
btnWifi.setVisibility(4);
warning.setText("This app may use your mobile data to update events and get their details.");
}
}
In the above code, if the result is false, (therefore there is no internet connection, the user is taken to the Android wi-fi panel, where he is prompted to connect to a wi-fi hotspot.
This method gives you the option for a really fast method (for real time feedback) or a slower method (for one off checks that require reliability)
public boolean isNetworkAvailable(bool SlowButMoreReliable) {
bool Result = false;
try {
if(SlowButMoreReliable){
ConnectivityManager MyConnectivityManager = null;
MyConnectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo MyNetworkInfo = null;
MyNetworkInfo = MyConnectivityManager.getActiveNetworkInfo();
Result = MyNetworkInfo != null && MyNetworkInfo.isConnected();
} else
{
Runtime runtime = Runtime.getRuntime();
Process ipProcess = runtime.exec("/system/bin/ping -c 1 8.8.8.8");
int i = ipProcess.waitFor();
Result = i== 0;
}
} catch(Exception ex)
{
//Common.Exception(ex); //This method is one you should have that displays exceptions in your log
}
return Result;
}
If the device is in airplane mode (or presumably in other situations where there's no available network), cm.getActiveNetworkInfo()
will be null
, so you need to add a null
check.
Modified (Eddie's solution) below:
public boolean isOnline() {
ConnectivityManager cm =
(ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = cm.getActiveNetworkInfo();
return netInfo != null && netInfo.isConnectedOrConnecting();
}
Also add the following permission to the AndroidManifest.xml
:
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
One other small point, if you absolutely need a network connection at the given point in time, then it might be better to use netInfo.isConnected()
rather than netInfo.isConnectedOrConnecting
. I guess this is up to the individual use-case however.
isConnectedOrConnecting()
(used in most answers) checks for any network connection// ICMP
public boolean isOnline() {
Runtime runtime = Runtime.getRuntime();
try {
Process ipProcess = runtime.exec("/system/bin/ping -c 1 8.8.8.8");
int exitValue = ipProcess.waitFor();
return (exitValue == 0);
}
catch (IOException e) { e.printStackTrace(); }
catch (InterruptedException e) { e.printStackTrace(); }
return false;
}
+
could run on main thread
-
does not work on some old devices (Galays S3, etc.), it blocks a while if no internet is available.
// TCP/HTTP/DNS (depending on the port, 53=DNS, 80=HTTP, etc.)
public boolean isOnline() {
try {
int timeoutMs = 1500;
Socket sock = new Socket();
SocketAddress sockaddr = new InetSocketAddress("8.8.8.8", 53);
sock.connect(sockaddr, timeoutMs);
sock.close();
return true;
} catch (IOException e) { return false; }
}
+
very fast (either way), works on all devices, very reliable
-
can't run on the UI thread
This works very reliably, on every device, and is very fast. It needs to run in a separate task though (e.g. ScheduledExecutorService
or AsyncTask
).
Is it really fast enough?
Yes, very fast ;-)
Is there no reliable way to check internet, other than testing something on the internet?
Not as far as I know, but let me know, and I will edit my answer.
What if the DNS is down?
Google DNS (e.g. 8.8.8.8
) is the largest public DNS in the world. As of 2013 it served 130 billion requests a day. Let 's just say, your app would probably not be the talk of the day.
Which permissions are required?
<uses-permission android:name="android.permission.INTERNET" />
Just internet access - surprise ^^ (Btw have you ever thought about, how some of the methods suggested here could even have a remote glue about internet access, without this permission?)
AsyncTask
Exampleclass InternetCheck extends AsyncTask<Void,Void,Boolean> {
private Consumer mConsumer;
public interface Consumer { void accept(Boolean internet); }
public InternetCheck(Consumer consumer) { mConsumer = consumer; execute(); }
@Override protected Boolean doInBackground(Void... voids) { try {
Socket sock = new Socket();
sock.connect(new InetSocketAddress("8.8.8.8", 53), 1500);
sock.close();
return true;
} catch (IOException e) { return false; } }
@Override protected void onPostExecute(Boolean internet) { mConsumer.accept(internet); }
}
///////////////////////////////////////////////////////////////////////////////////
// Usage
new InternetCheck(internet -> { /* do something with boolean response */ });
RxJava/RxAndroid
Example (Kotlin)fun hasInternetConnection(): Single<Boolean> {
return Single.fromCallable {
try {
// Connect to Google DNS to check for connection
val timeoutMs = 1500
val socket = Socket()
val socketAddress = InetSocketAddress("8.8.8.8", 53)
socket.connect(socketAddress, timeoutMs)
socket.close()
true
} catch (e: IOException) {
false
}
}
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
}
///////////////////////////////////////////////////////////////////////////////////
// Usage
hasInternetConnection().subscribe { hasInternet -> /* do something */}
Here is the method I use:
public boolean isNetworkAvailable(final Context context) {
return ((ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE)).getActiveNetworkInfo() != null;
}
Even better, check to make sure it is "connected":
public boolean isNetworkAvailable(final Context context) {
final ConnectivityManager connectivityManager = ((ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE));
return connectivityManager.getActiveNetworkInfo() != null && connectivityManager.getActiveNetworkInfo().isConnected();
}
Here is how to use the method:
if (isNetworkAvailable(context)) {
// code here
} else {
// code
}
Permission needed:
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
https://stackoverflow.com/a/16124915/950427