Detect whether there is an Internet connection available on Android [duplicate]

The getActiveNetworkInfo() method of ConnectivityManager returns a NetworkInfo instance representing the first connected network interface it can find or null if none of the interfaces are connected. Checking if this method returns null should be enough to tell if an internet connection is available or not.

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

You will also need:

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

in your android manifest.

Edit:

Note that having an active network interface doesn't guarantee that a particular networked service is available. Network issues, server downtime, low signal, captive portals, content filters and the like can all prevent your app from reaching a server. For instance you can't tell for sure if your app can reach Twitter until you receive a valid response from the Twitter service.

I check for both Wi-fi and Mobile internet as follows...

private boolean haveNetworkConnection() {
    boolean haveConnectedWifi = false;
    boolean haveConnectedMobile = false;

    ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo[] netInfo = cm.getAllNetworkInfo();
    for (NetworkInfo ni : netInfo) {
        if (ni.getTypeName().equalsIgnoreCase("WIFI"))
            if (ni.isConnected())
                haveConnectedWifi = true;
        if (ni.getTypeName().equalsIgnoreCase("MOBILE"))
            if (ni.isConnected())
                haveConnectedMobile = true;
    }
    return haveConnectedWifi || haveConnectedMobile;
}

Obviously, It could easily be modified to check for individual specific connection types, e.g., if your app needs the potentially higher speeds of Wi-fi to work correctly etc.

Step 1: Create a class AppStatus in your project(you can give any other name also). Then please paste the given below lines into your code:

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.util.Log;


public class AppStatus {

    private static AppStatus instance = new AppStatus();
    static Context context;
    ConnectivityManager connectivityManager;
    NetworkInfo wifiInfo, mobileInfo;
    boolean connected = false;

    public static AppStatus getInstance(Context ctx) {
        context = ctx.getApplicationContext();
        return instance;
    }

    public boolean isOnline() {
        try {
            connectivityManager = (ConnectivityManager) context
                        .getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
        connected = networkInfo != null && networkInfo.isAvailable() &&
                networkInfo.isConnected();
        return connected;


        } catch (Exception e) {
            System.out.println("CheckConnectivity Exception: " + e.getMessage());
            Log.v("connectivity", e.toString());
        }
        return connected;
    }
}

Step 2: Now to check if the your device has network connectivity then just add this code snippet where ever you want to check ...

if (AppStatus.getInstance(this).isOnline()) {

    Toast.makeText(this,"You are online!!!!",8000).show();

} else {

    Toast.makeText(this,"You are not online!!!!",8000).show();
    Log.v("Home", "############################You are not online!!!!");    
}

Also another important note. You have to set android.permission.ACCESS_NETWORK_STATE in your AndroidManifest.xml for this to work.

_ how could I have found myself the information I needed in the online documentation?

You just have to read the documentation the the classes properly enough and you'll find all answers you are looking for. Check out the documentation on ConnectivityManager. The description tells you what to do.

The getActiveNetworkInfo() method of ConnectivityManager returns a NetworkInfo instance representing the first connected network interface it can find or null if none if the interfaces are connected. Checking if this method returns null should be enough to tell if an internet connection is available.

private boolean isNetworkAvailable() {
     ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
     NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
     return activeNetworkInfo != null; 
}

You will also need:

in your android manifest.

Edit:

Note that having an active network interface doesn't guarantee that a particular networked service is available. Networks issues, server downtime, low signal, captive portals, content filters and the like can all prevent your app from reaching a server. For instance you can't tell for sure if your app can reach Twitter until you receive a valid response from the Twitter service.

getActiveNetworkInfo() shouldn't never give null. I don't know what they were thinking when they came up with that. It should give you an object always.