show toast when connectivity changes

Question

I built an app that streams audio using a webview. Now I added a check if there's connectivity (or not). Using toast I show a message with "true" or "false", but I'd like show a toast only when the connectivity changes. What should I do?

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

update();

private void update() {
        new Thread() {
            public void run() {
                while (true) {
                    runOnUiThread(new Runnable() {
                         @Override
                         public void run() {
                             isOnline();
                         }
                    });
                    try {
                        Thread.sleep(5000);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                } 
            }
        }.start();
        }


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

            Toast.makeText(getApplicationContext(), "true",Toast.LENGTH_LONG).show();   
            return true;
        }
        Toast.makeText(getApplicationContext(), "false",Toast.LENGTH_LONG).show();
        return false;

Answer 1

Try this :

public class BroadCastSampleActivity extends Activity {
        /** Called when the activity is first created. */
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            // TODO Auto-generated method stub
            super.onCreate(savedInstanceState);
            this.registerReceiver(this.mConnReceiver,
                    new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
        }
        private BroadcastReceiver mConnReceiver = new BroadcastReceiver() {
            public void onReceive(Context context, Intent intent) {
                boolean noConnectivity = intent.getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY, false);
                String reason = intent.getStringExtra(ConnectivityManager.EXTRA_REASON);
                boolean isFailover = intent.getBooleanExtra(ConnectivityManager.EXTRA_IS_FAILOVER, false);

                NetworkInfo currentNetworkInfo = (NetworkInfo) intent.getParcelableExtra(ConnectivityManager.EXTRA_NETWORK_INFO);
                NetworkInfo otherNetworkInfo = (NetworkInfo) intent.getParcelableExtra(ConnectivityManager.EXTRA_OTHER_NETWORK_INFO);

                if(currentNetworkInfo.isConnected()){
                    Toast.makeText(getApplicationContext(), "Connected", Toast.LENGTH_LONG).show();
                }else{
                    Toast.makeText(getApplicationContext(), "Not Connected", Toast.LENGTH_LONG).show();
                }
            }
        };
}

Add this permission in your Manifest :

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

Answer 2

You should register for android.net.conn.CONNECTIVITY_CHANGE. And show a dialog only on receiving the intent.

You can create an inner class that extends a BroadcastReceiver and shows a toast in it's onReceive method.

That should work :)

Answer 3

The ConnectivityManager broadcasts the CONNECTIVITY_ACTION ("android.net.conn.CONNECTIVITY_CHANGE") action whenever the connectivity details have changed. You can register a broadcast receiver in your manifest to listen for these changes and resume (or suspend) your background updates accordingly.

That comes from the android developer information.

You can read more here: http://developer.android.com/training/monitoring-device-state/connectivity-monitoring.html

That should have everything you need to show the toast notifications.