How to check currently internet connection is available or not in android

You can use two method :

1 - for check connection :

   private boolean isNetworkConnected() {
        ConnectivityManager cm = (ConnectivityManager) getContext().getSystemService(Context.CONNECTIVITY_SERVICE);
        return cm.getActiveNetworkInfo() != null;
    }

2 - for check internet :

  public boolean internetIsConnected() {
        try {
            String command = "ping -c 1 google.com";
            return (Runtime.getRuntime().exec(command).waitFor() == 0);
        } catch (Exception e) {
            return false;
        }
    }

Add permissions to manifest :

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

This will tell if you're connected to a network:

boolean connected = false;
ConnectivityManager connectivityManager = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
    if(connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState() == NetworkInfo.State.CONNECTED || 
            connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState() == NetworkInfo.State.CONNECTED) {
        //we are connected to a network
        connected = true;
    }
    else
        connected = false;

Warning: If you are connected to a WiFi network that doesn't include internet access or requires browser-based authentication, connected will still be true.

You will need this permission in your manifest:

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

Use Below Code:

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

if isNetworkAvailable() returns true then internet connection available, otherwise internet connection not available

Here need to add below uses-permission in your application Manifest file

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

Also, be aware that sometimes the user will be connected to a Wi-Fi network, but that network might require browser-based authentication. Most airport and hotel hotspots are like that, so you application might be fooled into thinking you have connectivity, and then any URL fetches will actually retrieve the hotspot's login page instead of the page you are looking for.

Depending on the importance of performing this check, in addition to checking the connection with ConnectivityManager, I'd suggest including code to check that it's a working Internet connection and not just an illusion. You can do that by trying to fetch a known address/resource from your site, like a 1x1 PNG image or 1-byte text file.