Android Activity LaunchMode attribute

activity-launchmode.xml

<activity android:launchMode = ["standard" | "singleTop" | "singleTask" | "singleInstance"] ../>

onNewIntent.java

protected void onNewIntent(Intent intent) {
    super.onNewIntent(intent);
    Uri uri = intent.getData();
    if (uri != null && uri.toString().startsWith(CALLBACK_URL)) {
        String verifier = uri.getQueryParameter("oauth_verifier");
        try {
            //load other persisted data goes here
            ....
            //get the request-token from prefs and request the access token
            TwitterFactory twitter = new TwitterFactory().getInstance();
            requestToken = prefsManager.getRequestToken();
            prefsManager.clearTwitterRequestToken();
            twitter4j.auth.AccessToken accessToken = twitter.getOAuthAccessToken(requestToken, verifier);
            // save the access token
            prefsManager.saveTwitterOauth(accessToken.getToken(), accessToken.getTokenSecret(), accessToken
                            .getScreenName());
            //other logics to do the post to twitter
            ....
         } catch (Exception e) {
             Log.e(TAG, e.getMessage(), e);
         }
    }
}

singleTask.xml

<activity android:name=".MainTabActivity" android:launchMode="singleTask" android:alwaysRetainTaskState="true" android:windowSoftInputMode="adjustPan">
</activity>

singletop.xml

 <activity android:name=".NewsDetailActivity" android:launchMode="singleTop">
      <intent-filter>
          <action android:name="android.intent.action.VIEW"></action>
          <category android:name="android.intent.category.DEFAULT"></category>  
          <category android:name="android.intent.category.BROWSABLE"></category>  
          <data android:scheme="oauth" android:host="twitt"></data>
      </intent-filter>
 </activity>

start-twitter-oauth.java

private void twitterOAuth() {
    try {
        System.setProperty("twitter4j.http.useSSL", "false");
        System.setProperty("twitter4j.oauth.consumerKey", getString(R.string.twitter_oauth_consumer_key));
        System.setProperty("twitter4j.oauth.consumerSecret", getString(R.string.twitter_oauth_consumer_secret));
        System.setProperty("twitter4j.oauth.requestTokenURL", "http://api.twitter.com/oauth/request_token");
        System.setProperty("twitter4j.oauth.accessTokenURL", "http://api.twitter.com/oauth/access_token");
        System.setProperty("twitter4j.oauth.authorizationURL", "http://api.twitter.com/oauth/authorize");

        // get the instance
        Twitter twitter = new TwitterFactory().getInstance();
        twitter4j.auth.RequestToken requestToken = twitter.getOAuthRequestToken(CALLBACK_URL);

        //save the request token and secret
        prefsManager.saveTwitterRequestToken(requestToken.getToken(), requestToken.getTokenSecret());
        //save other data
        persistNewsDatas();
        
        //start the browser activity
        Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(requestToken.getAuthenticationURL()));
        startActivity(intent);
    } catch (Exception e) {
        Log.e(TAG, e.getMessage(), e);
        Toast.makeText(NewsDetailActivity.this, "Fail to connect to twitter now, please try later.",
                    Toast.LENGTH_SHORT).show();
    }
}

Is this example correct? It always creates new instance of the NewsDetailActivity when returning back from Twitter web page.