How to Read Multiple NFC Tags Simultaneously in Android?

How can I read multiple NFC tags at the same time using Android devices?

// Example to set up NFC adapter
NfcAdapter nfcAdapter = NfcAdapter.getDefaultAdapter(this);

// Set up Intent to process NFC tags
PendingIntent pendingIntent = PendingIntent.getActivity(
    this, 0,
    new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP),
    0
);

Reading multiple NFC tags on Android is possible but comes with certain limitations and requires specific handling in your application. The Android NFC framework allows for tag discovery and processing, but the ability to read multiple tags simultaneously depends on the device capabilities and Android version.

@Override
protected void onNewIntent(Intent intent) {
    super.onNewIntent(intent);
    Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
    // Process the detected NFC tag
    readNfcTag(tag);
}

private void readNfcTag(Tag tag) {
    // Logic to extract information from the NFC tag
}

Causes

• NFC technology generally supports one tag at a time due to physical constraints.
• Default Android behavior processes one tag and then requires user action to read another.

Solutions

• Use the `NfcAdapter` class to handle NFC operations with an appropriate PendingIntent to manage incoming tag intents.
• Implement "Foreground Dispatch" to continuously listen for NFC tags even when your app is in the foreground.
• Handle `NfcAdapter.ACTION_TAG_DISCOVERED` intent in your activity to process each detected tag.

Mistake: Not handling intents properly; only the last detected tag is processed.

Solution: Ensure you implement foreground dispatch and check for incoming intents correctly to handle multiple tags.

Mistake: Assuming all NFC readers can handle multiple tags at once.

Solution: Understand hardware limitations and test on specific devices to determine capabilities.