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androidnfc

Android NfcAdapter.enableReaderMode callback not called

I'd like to, at a certain point in an app, request that the user scan an NFC tag. It seems like enableReaderMode would be a reasonable solution. However, it's not working - consider the following code placed in onCreate in an Activity in a new Android project (with the NFC permission added).

nfcAdapter = NfcAdapter.getDefaultAdapter(this);
if (nfcAdapter == null) {
    Toast.makeText(this, "No NFC", Toast.LENGTH_LONG).show();
    return;
}
System.out.println("NFC enable reader mode");
nfcAdapter.enableReaderMode(this, tag -> {
    System.out.println("NFC tag found");
    Toast.makeText(this, "Tag found", Toast.LENGTH_LONG).show();
}, NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK, null);

I see "NFC enable reader mode" in the logs, and (on one version of Android) while the app is up, tags do not cause other apps to open, suggesting that reader mode is indeed active (with FLAG_READER_SKIP_NDEF_CHECK preventing ndef checking), but the callback isn't called. I've held a tag to the back of the app, observed nothing, exited the app, and the tag immediately scans - so the tags are fine, and their placement is fine, just, for some reason enableReaderMode isn't causing the callback to get called when a tag gets near.

I've tried it on Oxygen OS 10, and on Android 11. On 10, it displayed the behavior given above. On 11, tags opened other apps, as normal (i.e. erroneously), rather than being suppressed by the ndef flag. Neither called the callback.

This seems like so basic a use case that, were it broken, I'd find dozens of threads about it, yet I've turned up only two sorta relevant things: on some device not call callback (NfcAdapter.ReaderCallback) method in nfcAdapter.enableReaderMode and NFCAdpater.enableReaderMode(...) doesn't work consistently if booting in Kiosk mode activity . The former looks pretty relevant, the latter less so, but neither are answered. I sorta figure I have to be doing something wrong - but it's such a simple block of code, I'm not sure what I COULD be doing wrong. Plus, there's the differing behavior between devices. Anybody know what's up?

Solution

  • You have configured enableReaderMode to skip Ndef detection BUT you have not configured it to read any other Tag Tech types

    Instead of NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK you flag options should look like below to be useful to read Tags

    NfcAdapter.FLAG_READER_NFC_A |
NfcAdapter.FLAG_READER_NFC_B |
NfcAdapter.FLAG_READER_NFC_F |
NfcAdapter.FLAG_READER_NFC_V |
NfcAdapter.FLAG_READER_NFC_BARCODE |
NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK |
NfcAdapter.FLAG_READER_NO_PLATFORM_SOUND