Disabling a JavaScript function when the device is offline

First, ensure your app has permission to access the network state by adding the following line to your AndroidManifest.xml:

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

Next, modify your code to check for internet connectivity before attempting to show the ad:

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.widget.Toast;

public class AdHandler {

    private Context context;

    public AdHandler(Context context) {
        this.context = context;
    }

    private boolean isOnline() {
        ConnectivityManager cm = 
            (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        if (cm != null) {
            NetworkInfo netInfo = cm.getActiveNetworkInfo();
            return (netInfo != null && netInfo.isConnected());
        }
        return false;
    }

    public void showAd(int adType) {
        if (adType == Sdkmanager.AD_REWARDED) {
            if (isOnline()) {
                Website2APK.showInterstitialAd();
            } else {
                // No internet connection
                // ...
            }
        }
    }
}