Identifying NFC tag ID

Question

I am trying to identify the unique identifier of NFC tag on android using the following code:

@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 Tag myTag = (Tag) getIntent().getParcelableExtra(NfcAdapter.EXTRA_TAG);
 String nFCID = myTag.getId().toString();   
 Toast.makeText(getApplicationContext(), "NFC id is: "+ nFCID, Toast.LENGTH_SHORT).show();      
}

Unfortunately, when I deploy the app to a real device and scan an NFC tag, my app will crash stating "Unfortunately xyz has to stop...". I know getID() will return byte array and I have to parse it to String. But at least I expect this code to return some values rather than crashing the app. Any ideas how to fix it?

Edited: LogCat outputs:

W/dalvikvm(25548): threadid=1: thread exiting with uncaught exception group=0x41b652a0)
E/AndroidRuntime(25548): FATAL EXCEPTION: main
E/AndroidRuntime(25548): java.lang.RuntimeException: 
Unable to start activity ComponentInfo{com.xyz.nfcid/com.xyz.nfcid.MainActivity}: 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2100)

Are you sure myTag isn't null? – dymmeh Aug 19 '13 at 20:26 — dymmeh, Aug 19 '13 at 20:26
What happens if you do this on onResume() ? – ThomasRS Aug 22 '13 at 16:51 — ThomasRS, Aug 22 '13 at 16:51

score 0 · Answer 1 · answered Aug 19 '13 at 20:33

0

I'm pretty sure, that your tag is null. You should check the action String first

String action = intent.getAction();
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)) {
    //... do something
}

I've written a complete tutorial, which should help you.

answered Aug 19 '13 at 20:33

vRallev

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I am sure the tag is not null. Using "NFC TagInfo" app, I checked that the tag has NDEF message to start the main activity of my app. I will check ur tutorial now. – Dangila Aug 19 '13 at 21:06
What's the reason for the exception? Please provide us the stacktrace. – vRallev Aug 19 '13 at 21:07
just added the LogCat output to the main question. – Dangila Aug 19 '13 at 21:25
There should be more output. Did you add the NFC permission? – vRallev Aug 20 '13 at 05:19

Identifying NFC tag ID

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