Question

I am creating a class to check internet connectivity, I am getting below error :

 12-16 10:34:07.340: E/AndroidRuntime(1099):

java.lang.NullPointerException 12-16 10:34:07.340:
E/AndroidRuntime(1099): at
com.internetchecker.main.InternetCheckerActivity$1.onClick(InternetCheckerActivity.java:25)
12-16 10:34:07.340: E/AndroidRuntime(1099): at
android.view.View.performClick(View.java:2485) 12-16 10:34:07.340:
E/AndroidRuntime(1099): at
android.view.View$PerformClick.run(View.java:9080) 12-16 10:34:07.340:
E/AndroidRuntime(1099): at
android.os.Handler.handleCallback(Handler.java:587) 12-16
10:34:07.340: E/AndroidRuntime(1099): at
android.os.Handler.dispatchMessage(Handler.java:92) 12-16
10:34:07.340: E/AndroidRuntime(1099): at
android.os.Looper.loop(Looper.java:123) 12-16 10:34:07.340:
E/AndroidRuntime(1099): at
android.app.ActivityThread.main(ActivityThread.java:3683) 12-16
10:34:07.340: E/AndroidRuntime(1099): at
java.lang.reflect.Method.invokeNative(Native Method) 12-16
10:34:07.340: E/AndroidRuntime(1099): at
java.lang.reflect.Method.invoke(Method.java:507) 12-16 10:34:07.340:
E/AndroidRuntime(1099): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
12-16 10:34:07.340: E/AndroidRuntime(1099): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 12-16
10:34:07.340: E/AndroidRuntime(1099): at
dalvik.system.NativeStart.main(Native Method)

The code of my Class is below :

public class CheckInternet2 {
private static Boolean status =  true;
public static Boolean isConnected() {
    Runnable runnable = new Runnable() {
        public void run() {
            // TODO Auto-generated method stub
            isNetworkAvailable(h,2000);             
        }           
    };
    runnable.run();
    return status;
}
private static Handler h = new Handler() {

    @Override
    public void handleMessage(Message msg) {

        if (msg.what != 1) { // code if not connected
            status = false;
            System.out.println("Status False");
        } else { // code if connected
            status = true;
            System.out.println("Status True");
        }
    }
};

private static  void isNetworkAvailable(final Handler handler, final int timeout) {

    new Thread() {

        private boolean responded = false;
        @Override
        public void run() {

            new Thread() {
                @Override
                public void run() {
                    HttpGet requestForTest = new HttpGet("http://m.google.com");
                    try {
                        new DefaultHttpClient().execute(requestForTest); // can last...
                        responded = true;
                    } catch (Exception e) {}
                }
            }.start();
            try {
                int waited = 0;
                while(!responded && (waited < timeout)) {
                    sleep(100);
                    if(!responded ) { 
                        waited += 100;
                    }
                }
            } 
            catch(InterruptedException e) {} // do nothing 
            finally { 
                if (!responded) { handler.sendEmptyMessage(0);
                } 
                else { handler.sendEmptyMessage(1); 
                }
            }
        }
    }.start();
}
}

and I am calling it as :

btnCheckStatus.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                if(CheckInternet2.isConnected())
                {
                    Toast.makeText(getApplicationContext(), "Connected ", 0).show();
                }
                else
                {
                    Toast.makeText(getApplicationContext(), "Not Connected ", 0).show();
                }


            }
        });

I am not able to figure out why its throwing exception.

Answer 1

check for the network availability along with wifi status

To Check Network Availability

public static boolean isNetworkPresent(Context context) {
        boolean isNetworkAvailable = false;
        ConnectivityManager cm = (ConnectivityManager) context
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        try {

            if (cm != null) {
                NetworkInfo netInfo = cm.getActiveNetworkInfo();
                if (netInfo != null) {
                    isNetworkAvailable = netInfo.isConnectedOrConnecting();
                }
            }
        } catch (Exception ex) {
            Log.e("Network Avail Error", ex.getMessage());
        }
        //check for wifi also
        if(!isNetworkAvailable){
            WifiManager connec = (WifiManager) context
                    .getSystemService(Context.WIFI_SERVICE);
            State wifi = cm.getNetworkInfo(1).getState();
            if (connec.isWifiEnabled()
                    && wifi.toString().equalsIgnoreCase("CONNECTED")) {
                isNetworkAvailable = true;
            } else {

                isNetworkAvailable = false;
            }

        }
        return isNetworkAvailable;
    }