App이 켜진 상태에서 말씀하시는 거면 소스에
onCreate에
{
...
adapter = NfcAdapter.getDefaultAdapter(this);
pendingIntent = PendingIntent.getActivity(this, 0, new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
IntentFilter tagDetected = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED);
tagDetected.addCategory(Intent.CATEGORY_DEFAULT);
writeTagFilters = new IntentFilter[] { tagDetected };
...
}
하고
@Override
protected void onNewIntent(Intent intent){
if(NfcAdapter.ACTION_TAG_DISCOVERED.equals(intent.getAction())){
mytag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
Toast.makeText(mContext, "Tag연결됨 : " + mytag.toString(), Toast.LENGTH_LONG ).show();
}
}
추가해보세요.