How to read and write to a NfcA card from Android

Question

I've made an app that is called when the intent android.nfc.action.TAG_DISCOVERED is sent, but then I want to get the info of the card in the onNewIntent method, but I don't know how to handle this kind of nfc cards. I tried with the following code:

    public void onNewIntent(Intent intent) {
        Tag tagFromIntent = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
        //do something with tagFromIntent
        NfcA nfca = NfcA.get(tagFromIntent);
        try{
            nfca.connect();
            Short s = nfca.getSak();
            byte[] a = nfca.getAtqa();
            String atqa = new String(a, Charset.forName("US-ASCII"));
            tv.setText("SAK = "+s+"\nATQA = "+atqa);
            nfca.close();
        }
        catch(Exception e){
            Log.e(TAG, "Error when reading tag");
            tv.setText("Error");
        }
    }

tv is a TextView, but when this code is executed it never gets changed.

Answer 1

OnNewIntent is called if your activity is already running and is set to be singleTask. You'll want to make the code it's own method and call it in onCreate() as well as onNewIntent()