NFC P2P tag intercept

I am building an Android app using Eclipse and Android SDK. I would like to implement an NFC P2P function in my app in the sense that when you place the 2 phones back to back, both send a string and receive a string automatically. This would of course happen in a separate activity. I have managed to send a custom tag (String) but have been unable to intercept it and use it afterwards in the app code. How can I do this?

This is what I have so far:

public class MainActivity extends Activity {

public NfcAdapter mAdapter;
PendingIntent mPendingIntent;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.activity_main);


     mAdapter = NfcAdapter.getDefaultAdapter(this);

     NdefRecord rec = NdefRecord.createUri("http://ift.tt/fyw30c"); 
     NdefMessage ndef = new NdefMessage(rec);

     mAdapter.setNdefPushMessage(ndef, this);
 }

I have spent a lot of time trying to find and understand solutions to intercept the tag. Unsuccessfully.

Thank you for your help.