Detect if Android device has Internet connection

You can do this with very simple class.

class CheckInternet {
    fun isNetworkAvailable(context: Context): Boolean {
        val connectivityManager =
            context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager?
        val activeNetworkInfo = connectivityManager!!.activeNetworkInfo
        return activeNetworkInfo != null && activeNetworkInfo.isConnected
    }
}

Now you can check this from any class.

if (CheckInternet().isNetworkAvailable(this)) {
  //connected with internet
}else{
  //Not connected with internet
}

You can do this using the ConnectivityManager API for android. It allows you to check whether you are connected to the internet and the type of internet connection you are connected to. Basically, Metered or Un-metered.

To check for internet connection.

ConnectivityManager cm = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
boolean isConnected = activeNetwork != null && activeNetwork.isConnectedOrConnecting();

Documentation link: https://developer.android.com/training/monitoring-device-state/connectivity-status-type

The latest way to do that from the documentation is to use the ConnectivityManager to query the active network and determine if it has Internet connectivity.

public boolean hasInternetConnectivity() {
    ConnectivityManager cm =
        (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);

    NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
    return (activeNetwork != null &&
                      activeNetwork.isConnectedOrConnecting());
}

Add these two permissions to your AndroidManifest.xml file:

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

Check wifi type in connectivity manager:

   //check network connection
    ConnectivityManager cm = (ConnectivityManager) this.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
    boolean hasNetworkConnection = activeNetwork != null && activeNetwork.isConnectedOrConnecting();
    System.out.println("Connection ? : " + hasNetworkConnection);
    //check wifi
    boolean hasWifiConnection = activeNetwork.getType() == ConnectivityManager.TYPE_WIFI;
    System.out.println("Wifi ? : " + hasWifiConnection);

Android Documentation describes 'TYPE_WIFI' as 'A WIFI data connection. Devices may support more than one.'

A nice solution to check if the active network have internet connection:

public boolean isNetworkAvailable(Context context) {
    ConnectivityManager connectivityManager
            = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    if (connectivityManager != null) {
        Network network = connectivityManager.getActiveNetwork();
        NetworkCapabilities networkCapabilities = connectivityManager.getNetworkCapabilities(network);
        return networkCapabilities != null && networkCapabilities
                .hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET);
    }
    return false;
}

You can use ConnectivityManager.

val cm = getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
            val activeNetwork: NetworkInfo? = cm.activeNetworkInfo
            val dialogBuilder = AlertDialog.Builder(this)

            if (activeNetwork!=null) // Some network is available
            {
                if (activeNetwork.isConnected) { // Network is connected to internet

    }else{ // Network is NOT connected to internet

    }

Check this and this

Use the following class, updated to the last API level: 29.

// License: MIT
// http://opensource.org/licenses/MIT
package net.i2p.android.router.util;

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.Network;
import android.net.NetworkCapabilities;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Build;
import android.telephony.TelephonyManager;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.concurrent.CancellationException;



/**
 * Check device's network connectivity and speed.
 *
 * @author emil http://stackoverflow.com/users/220710/emil
 * @author str4d
 * @author rodrigo https://stackoverflow.com/users/5520417/rodrigo
 */
public class ConnectivityAndInternetAccessCheck {

    private static ArrayList < String > hosts = new ArrayList < String > () {
        {
            add("google.com");
            add("facebook.com");
            add("apple.com");
            add("amazon.com");
            add("twitter.com");
            add("linkedin.com");
            add("microsoft.com");
        }
    };
    /**
     * Get the network info.
     *
     * @param context the Context.
     * @return the active NetworkInfo.
     */
    private static NetworkInfo getNetworkInfo(Context context) {
        NetworkInfo networkInfo = null;
        ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        if (cm != null) {
            networkInfo = cm.getActiveNetworkInfo();
        }
        return networkInfo;
    }

    /**
     * Gets the info of all networks
     * @param context The context
     * @return an array of @code{{@link NetworkInfo}}
     */
    private static NetworkInfo[] getAllNetworkInfo(Context context) {
        ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        return cm.getAllNetworkInfo();
    }

    /**
     * Gives the connectivity manager
     * @param context The context
     * @return the @code{{@link ConnectivityManager}}
     */
    private static ConnectivityManager getConnectivityManager(Context context) {
        return (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    }

    /**
     * Check if there is any connectivity at all.
     *
     * @param context the Context.
     * @return true if we are connected to a network, false otherwise.
     */
    public static boolean isConnected(Context context) {
        boolean isConnected = false;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            ConnectivityManager connectivityManager = ConnectivityAndInternetAccessCheck.getConnectivityManager(context);
            Network[] networks = connectivityManager.getAllNetworks();
            networksloop: for (Network network: networks) {
                if (network == null) {
                    isConnected = false;
                } else {
                    NetworkCapabilities networkCapabilities = connectivityManager.getNetworkCapabilities(network);
                    if(networkCapabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)){
                        isConnected = true;
                        break networksloop;
                    }
                    else {
                        isConnected = false;
                    }
                }
            }

        } else {
            NetworkInfo[] networkInfos = ConnectivityAndInternetAccessCheck.getAllNetworkInfo(context);
            networkinfosloop: for (NetworkInfo info: networkInfos) {
                // Works on emulator and devices.
                // Note the use of isAvailable() - without this, isConnected() can
                // return true when Wifi is disabled.
                // http://stackoverflow.com/a/2937915
                isConnected = info != null && info.isAvailable() && info.isConnected();
                if (isConnected) {
                    break networkinfosloop;
                }
            }

        }
        return isConnected;
    }

    /**
     * Check if there is any connectivity to a Wifi network.
     *
     * @param context the Context.
     * @return true if we are connected to a Wifi network, false otherwise.
     */
    public static boolean isConnectedWifi(Context context) {
        boolean isConnectedWifi = false;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            ConnectivityManager connectivityManager = ConnectivityAndInternetAccessCheck.getConnectivityManager(context);
            Network[] networks = connectivityManager.getAllNetworks();
            networksloop: for (Network network: networks) {
                if (network == null) {
                    isConnectedWifi = false;
                } else {
                    NetworkCapabilities networkCapabilities = connectivityManager.getNetworkCapabilities(network);
                    if(networkCapabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)){
                        if (networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_WIFI)) {
                            isConnectedWifi = true;
                            break networksloop;
                        } else {
                            isConnectedWifi = false;
                        }
                    }
                }

            }


        } else {
            NetworkInfo[] networkInfos = ConnectivityAndInternetAccessCheck.getAllNetworkInfo(context);
            networkinfosloop: for (NetworkInfo n: networkInfos) {
                isConnectedWifi = n != null && n.isAvailable() && n.isConnected() && n.getType() == ConnectivityManager.TYPE_WIFI;
                if (isConnectedWifi) {
                    break networkinfosloop;
                }

            }
        }
        return isConnectedWifi;
    }

    /**
     * Check if there is any connectivity to a mobile network.
     *
     * @param context the Context.
     * @return true if we are connected to a mobile network, false otherwise.
     */
    public static boolean isConnectedMobile(Context context) {
        boolean isConnectedMobile = false;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            ConnectivityManager connectivityManager = ConnectivityAndInternetAccessCheck.getConnectivityManager(context);
            Network[] allNetworks = connectivityManager.getAllNetworks();
            networksloop: for (Network network: allNetworks) {
                if (network == null) {
                    isConnectedMobile = false;
                } else {
                    NetworkCapabilities networkCapabilities = connectivityManager.getNetworkCapabilities(network);
                    if(networkCapabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)){
                        if (networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR)) {
                            isConnectedMobile = true;
                            break networksloop;
                        } else {
                            isConnectedMobile = false;
                        }
                    }
                }

            }

        } else {
            NetworkInfo[] networkInfos = ConnectivityAndInternetAccessCheck.getAllNetworkInfo(context);
            networkinfosloop: for (NetworkInfo networkInfo: networkInfos) {
                isConnectedMobile = networkInfo != null && networkInfo.isAvailable() && networkInfo.isConnected() && networkInfo.getType() == ConnectivityManager.TYPE_MOBILE;
                if (isConnectedMobile) {
                    break networkinfosloop;
                }
            }
        }
        return isConnectedMobile;
    }

    /**
     * Check if there is fast connectivity.
     *
     * @param context the Context.
     * @return true if we have "fast" connectivity, false otherwise.
     */
    public static boolean isConnectedFast(Context context) {
        boolean isConnectedFast = false;
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
            NetworkInfo[] networkInfos = ConnectivityAndInternetAccessCheck.getAllNetworkInfo(context);
            networkInfosloop:
            for (NetworkInfo networkInfo: networkInfos) {
                isConnectedFast = networkInfo != null && networkInfo.isAvailable() && networkInfo.isConnected() && isConnectionFast(networkInfo.getType(), networkInfo.getSubtype());
                if (isConnectedFast) {
                    break networkInfosloop;
                }
            }
        } else {
            throw new UnsupportedOperationException();
        }
        return isConnectedFast;
    }

    /**
     * Check if the connection is fast.
     *
     * @param type the network type.
     * @param subType the network subtype.
     * @return true if the provided type/subtype combination is classified as fast.
     */
    private static boolean isConnectionFast(int type, int subType) {
        if (type == ConnectivityManager.TYPE_WIFI) {
            return true;
        } else if (type == ConnectivityManager.TYPE_MOBILE) {
            switch (subType) {
                case TelephonyManager.NETWORK_TYPE_1xRTT:
                    return false; // ~ 50-100 kbps
                case TelephonyManager.NETWORK_TYPE_CDMA:
                    return false; // ~ 14-64 kbps
                case TelephonyManager.NETWORK_TYPE_EDGE:
                    return false; // ~ 50-100 kbps
                case TelephonyManager.NETWORK_TYPE_EVDO_0:
                    return true; // ~ 400-1000 kbps
                case TelephonyManager.NETWORK_TYPE_EVDO_A:
                    return true; // ~ 600-1400 kbps
                case TelephonyManager.NETWORK_TYPE_GPRS:
                    return false; // ~ 100 kbps
                case TelephonyManager.NETWORK_TYPE_HSDPA:
                    return true; // ~ 2-14 Mbps
                case TelephonyManager.NETWORK_TYPE_HSPA:
                    return true; // ~ 700-1700 kbps
                case TelephonyManager.NETWORK_TYPE_HSUPA:
                    return true; // ~ 1-23 Mbps
                case TelephonyManager.NETWORK_TYPE_UMTS:
                    return true; // ~ 400-7000 kbps
                /*
                 * Above API level 7, make sure to set android:targetSdkVersion
                 * to appropriate level to use these
                 */
                case TelephonyManager.NETWORK_TYPE_EHRPD: // API level 11
                    return true; // ~ 1-2 Mbps
                case TelephonyManager.NETWORK_TYPE_EVDO_B: // API level 9
                    return true; // ~ 5 Mbps
                case TelephonyManager.NETWORK_TYPE_HSPAP: // API level 13
                    return true; // ~ 10-20 Mbps
                case TelephonyManager.NETWORK_TYPE_IDEN: // API level 8
                    return false; // ~25 kbps
                case TelephonyManager.NETWORK_TYPE_LTE: // API level 11
                    return true; // ~ 10+ Mbps
                // Unknown
                case TelephonyManager.NETWORK_TYPE_UNKNOWN:
                default:
                    return false;
            }
        } else {
            return false;
        }
    }

    public ArrayList < String > getHosts() {
        return hosts;
    }

    public void setHosts(ArrayList < String > hosts) {
        this.hosts = hosts;
    }
    //TODO Debug on devices
    /**
     * Checks that Internet is available by pinging DNS servers.
     */
    private static class InternetConnectionCheckAsync extends AsyncTask < Void, Void, Boolean > {

        private Context context;

        /**
         * Creates an instance of this class
         * @param context The context
         */
        public InternetConnectionCheckAsync(Context context) {
            this.setContext(context);
        }

        /**
         * Cancels the activity if the device is not connected to a network.
         */
        @Override
        protected void onPreExecute() {
            if (!ConnectivityAndInternetAccessCheck.isConnected(getContext())) {
                cancel(true);
            }
        }

        /**
         * Tells whether there is Internet access
         * @param voids The list of arguments
         * @return True if Internet can be accessed
         */
        @Override
        protected Boolean doInBackground(Void...voids) {
            return isConnectedToInternet(getContext());
        }

        @Override
        protected void onPostExecute(Boolean aBoolean) {
            super.onPostExecute(aBoolean);
        }

        /**
         * The context
         */
        public Context getContext() {
            return context;
        }

        public void setContext(Context context) {
            this.context = context;
        }
    } //network calls shouldn't be called from main thread otherwise it will throw //NetworkOnMainThreadException

    /**
     * Tells whether Internet is reachable
     * @return true if Internet is reachable, false otherwise
     * @param context The context
     */
    public static boolean isInternetReachable(Context context) {
        try {
            return new InternetConnectionCheckAsync(context).execute().get();
        } catch (CancellationException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    /**
     * Tells whether there is Internet connection
     * @param context The context
     * @return @code {true} if there is Internet connection
     */
    private static boolean isConnectedToInternet(Context context) {
        boolean isAvailable = false;
        if (!ConnectivityAndInternetAccessCheck.isConnected(context)) {
            isAvailable = false;
        } else {
            try {
                foreachloop: for (String h: new ConnectivityAndInternetAccessCheck().getHosts()) {
                    if (isHostAvailable(h)) {
                        isAvailable = true;
                        break foreachloop;
                    }
                }
            }
            catch (IOException e) {
                e.printStackTrace();
            }
        }

        return isAvailable;

    }

    /**
     * Checks if the host is available
     * @param hostName
     * @return
     * @throws IOException
     */
    private static boolean isHostAvailable(String hostName) throws IOException {
        try (Socket socket = new Socket()) {
            int port = 80;
            InetSocketAddress socketAddress = new InetSocketAddress(hostName, port);
            socket.connect(socketAddress, 3000);

            return true;
        } catch (UnknownHostException unknownHost) {
            return false;
        }
    }
}

If all above answers get you FATAL EXCEPTIONs like android.os.NetworkOnMainThreadException, this answer will really help you.
Because I got this error while trying to implement this.

The reason for this error is that the Network related codes cannot be on the main thread.
So, you need to create a new Thread as I shown below:

Thread thread = new Thread(new Runnable() {

@Override
public void run() {
    try  {
        //Your code goes here
    } catch (Exception e) {
        e.printStackTrace();
    }
}});

And put your code in the place I commented.