Android : Check 3G or Wifi network is ON or Available or not on android Device

You can use this method to check whether your internet connection is 2G, 3G or 4G:

public String getNetworkClass(Context context) {
    TelephonyManager mTelephonyManager = (TelephonyManager)
            context.getSystemService(Context.TELEPHONY_SERVICE);
    int networkType = mTelephonyManager.getNetworkType();
    switch (networkType) {
        case TelephonyManager.NETWORK_TYPE_GPRS:
        case TelephonyManager.NETWORK_TYPE_EDGE:
        case TelephonyManager.NETWORK_TYPE_CDMA:
        case TelephonyManager.NETWORK_TYPE_1xRTT:
        case TelephonyManager.NETWORK_TYPE_IDEN:
            return "2G";
        case TelephonyManager.NETWORK_TYPE_UMTS:
        case TelephonyManager.NETWORK_TYPE_EVDO_0:
        case TelephonyManager.NETWORK_TYPE_EVDO_A:
        case TelephonyManager.NETWORK_TYPE_HSDPA:
        case TelephonyManager.NETWORK_TYPE_HSUPA:
        case TelephonyManager.NETWORK_TYPE_HSPA:
        case TelephonyManager.NETWORK_TYPE_EVDO_B:
        case TelephonyManager.NETWORK_TYPE_EHRPD:
        case TelephonyManager.NETWORK_TYPE_HSPAP:
            return "3G";
        case TelephonyManager.NETWORK_TYPE_LTE:
            return "4G";
        default:
            return "Unknown";
    }
}

And using following method you can check if internet is available or not, and get whether you are accessing the internet via a mobile network or WiFi:

public String getNetworkType(Context context){
    String networkType = null;
    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetwork = connectivityManager.getActiveNetworkInfo();
    if (activeNetwork != null) { // connected to the internet
        if (activeNetwork.getType() == ConnectivityManager.TYPE_WIFI) {
                networkType = "WiFi";
        } else if (activeNetwork.getType() == ConnectivityManager.TYPE_MOBILE) {
            networkType = "Mobile";
        }
    } else {
        // not connected to the internet
    }
    return networkType;
}

TO check whether network i.e 3G or WiFi is available or not we can use below methods to verify before starting our activities.

ConnectivityManager manager = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);

//For 3G check
boolean is3g = manager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE)
            .isConnectedOrConnecting();
//For WiFi Check
boolean isWifi = manager.getNetworkInfo(ConnectivityManager.TYPE_WIFI)
            .isConnectedOrConnecting();

System.out.println(is3g + " net " + isWifi);

if (!is3g && !isWifi) 
{ 
Toast.makeText(getApplicationContext(),"Please make sure your Network Connection is ON ",Toast.LENGTH_LONG).show();
} 
 else 
{ 
        " Your method what you want to do "
} 

Hope this will help someone.

This work for me

NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();   
String name networkInfo.getTypeName();  

final ConnectivityManager connMgr = (ConnectivityManager)
    this.getSystemService(Context.CONNECTIVITY_SERVICE);

    final android.net.NetworkInfo wifi =
    connMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI);

    final android.net.NetworkInfo mobile =
    connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);

    if( wifi.isAvailable() && wifi.getDetailedState() == DetailedState.CONNECTED){
        Toast.makeText(this, "Wifi" , Toast.LENGTH_LONG).show();
    }
    else if( mobile.isAvailable() && mobile.getDetailedState() == DetailedState.CONNECTED ){
        Toast.makeText(this, "Mobile 3G " , Toast.LENGTH_LONG).show();
    }
    else
    {   
        Toast.makeText(this, "No Network " , Toast.LENGTH_LONG).show();
    }

this code check if you are with wifi or 3g or nothing , in the case of wifi on but not connected to a net or 3g have signal problem it detect this details, with DetailedStates