show toast when connectivity changes
<p>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?</p>

<pre><code>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 &amp;&amp; netInfo.isConnectedOrConnecting()) {

            Toast.makeText(getApplicationContext(), "true",Toast.LENGTH_LONG).show();   
            return true;
        }
        Toast.makeText(getApplicationContext(), "false",Toast.LENGTH_LONG).show();
        return false;
</code></pre>
