Create Dialog Box For Checking Internet Connection in Android

Question

I'm implementing to show dialog box when Internet is offline, when i run my app i got "FATAL Exception main" and ClassCastException when when i click on button and application is crash . Can someone tell me what i am doing wrong ? Thanks to you in Advanced.

here is code how i check is internet enabled or not:

public class AndroidDetectInternetConnectionActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Button btnStatus = (Button) findViewById(R.id.btn_check);

        btnStatus.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {


                if (!isOnline())
                {
                    showNoConnectionDialog(this);

                }
            }

        });

    }

    public static void showNoConnectionDialog(OnClickListener onClickListener) 
    {
        final Context ctx = (Context) onClickListener;
        AlertDialog.Builder builder = new AlertDialog.Builder(ctx);
        builder.setCancelable(true);
        builder.setMessage(R.string.no_connection);
        builder.setTitle(R.string.no_connection_title);
        builder.setPositiveButton(R.string.settings_button_text, new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) 
            {

                ctx.startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));
            }
        });

        builder.setNegativeButton(R.string.cancel_button_text, new DialogInterface.OnClickListener() 
        {
            public void onClick(DialogInterface dialog, int which) 
            {
                return;
            }
        });

        builder.setOnCancelListener(new DialogInterface.OnCancelListener() 
        {
            public void onCancel(DialogInterface dialog) {
                return;
            }
        });

        builder.show();
    }

    public boolean isOnline() 
    {
        ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo netInfo = cm.getActiveNetworkInfo();
        if (netInfo != null && netInfo.isConnectedOrConnecting()) 
        {
            return true;
        }
        return false;
    }

}

// This is my Log Cat stack trace

11-15 11:57:19.115: D/AndroidRuntime(453): Shutting down VM
11-15 11:57:19.115: W/dalvikvm(453): threadid=1: thread exiting with uncaught exception (group=0x40015560)
11-15 11:57:19.122: E/AndroidRuntime(453): FATAL EXCEPTION: main
11-15 11:57:19.122: E/AndroidRuntime(453): java.lang.ClassCastException: com.example.detectinternetconnection.AndroidDetectInternetConnectionActivity$1
11-15 11:57:19.122: E/AndroidRuntime(453):  at com.example.detectinternetconnection.AndroidDetectInternetConnectionActivity.showNoConnectionDialog(AndroidDetectInternetConnectionActivity.java:99)
11-15 11:57:19.122: E/AndroidRuntime(453):  at com.example.detectinternetconnection.AndroidDetectInternetConnectionActivity$1.onClick(AndroidDetectInternetConnectionActivity.java:64)
11-15 11:57:19.122: E/AndroidRuntime(453):  at android.view.View.performClick(View.java:2485)
11-15 11:57:19.122: E/AndroidRuntime(453):  at android.view.View$PerformClick.run(View.java:9080)
11-15 11:57:19.122: E/AndroidRuntime(453):  at android.os.Handler.handleCallback(Handler.java:587)
11-15 11:57:19.122: E/AndroidRuntime(453):  at android.os.Handler.dispatchMessage(Handler.java:92)
11-15 11:57:19.122: E/AndroidRuntime(453):  at android.os.Looper.loop(Looper.java:123)
11-15 11:57:19.122: E/AndroidRuntime(453):  at android.app.ActivityThread.main(ActivityThread.java:3683)
11-15 11:57:19.122: E/AndroidRuntime(453):  at java.lang.reflect.Method.invokeNative(Native Method)
11-15 11:57:19.122: E/AndroidRuntime(453):  at java.lang.reflect.Method.invoke(Method.java:507)
11-15 11:57:19.122: E/AndroidRuntime(453):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
11-15 11:57:19.122: E/AndroidRuntime(453):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
11-15 11:57:19.122: E/AndroidRuntime(453):  at dalvik.system.NativeStart.main(Native Method)
11-15 11:57:24.892: I/Process(453): Sending signal. PID: 453 SIG: 9

Answer 1

change this line

 final Context ctx = (Context) onClickListener;

to below one

 final Context ctx = AndroidDetectInternetConnectionActivity.this;

basically you are trying to conver onClickListener to Contex which is incorrect and can not be casted. Either you directly use ActivityName.this wherever you need context instance, or define static Context ctx as a class variable and intialize it in onCreate() by just adding this line ctx =this also remember to intialize it before using it.

Enjoy

Answer 2

There are two ways to solve this problem.

1) showNoConnectionDialog(this); and later on: public static void showNoConnectionDialog(Context ctx) ...

2) showNoConnectionDialog(); and later on: public void showNoConnectionDialog() { Context ctx = AndroidDetectInternetConnectionActivity.this

Answer 3

You basic problem is generated by the line:

final Context ctx = (Context) onClickListener;

This is simply not a context so trying to force it to be one doesn't work.

I believe that you wanted to do was pass a context (or activity) to this function (as opposed to the local unnamed OnClickListener class that you are now passing)

The easiest solution would be to simple not pass anything to the constructor and use AndroidDetectInternetConnectionActivity.this to access your valid context.