[android-developers] Re: NdefRecord(NdefMessage) extraction from the intent in a NFC design
Though, some of the extras, especially EXTRA_NDEF_MESSAGES, might be null. All the extras provided by an intent behave as a map, i.e. if the extra is not defined, then null is returned, so you can also ask for the extra intent.getStringExtra(android.nfc.extra.SOMETHING) and you will get null as result (as this entry is not available); exceptions are never thrown. So if you say that EXTRA_NDEF_MESSAGES might be null, this means that this extra is not available. According to the documentation, only getParcelableExtra(NfcAdapter.EXTRA_TAG) is guaranteed to be non-null. Dominik -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] Re: NdefRecord(NdefMessage) extraction from the intent in a NFC design
Hallo Dominik,
What do you mean by all three NFC intents *have* three extras? I
ask, because the documentation at
http://developer.android.com/reference/android/nfc/NfcAdapter.html
states, that EXTRA_ID and EXTRA_NDEF_MESSAGES are optional (which is
obvious for the latter) and only EXTRA_TAG is mandatory.
Correct. Those intent extras are listed as optional. Still the current
implementation (or at least the one in Android 2.3.4) adds all three
extras to every intent. Though, some of the extras, especially
EXTRA_NDEF_MESSAGES, might be null.
Anyway, in which case is the ID field not available?
I don't think that there is any case where the ID field will be
empty/not available. For NFC/RFID tags there will always be an ID field.
Even for the NDEF push protocol a mock tag with an ID of
new byte[] { 0x00 }
is used.
br,
Michael
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[android-developers] Re: NdefRecord(NdefMessage) extraction from the intent in a NFC design
What do you mean by all three NFC intents *have* three extras? I ask, because the documentation at http://developer.android.com/reference/android/nfc/NfcAdapter.html states, that EXTRA_ID and EXTRA_NDEF_MESSAGES are optional (which is obvious for the latter) and only EXTRA_TAG is mandatory. Anyway, in which case is the ID field not available? Dominik -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
[android-developers] Re: NdefRecord(NdefMessage) extraction from the intent in a NFC design
Hallo, first of all, the prefered method of receiving tag detection events is the android.nfc.action.TECH_DISCOVERED intent, the intent android.nfc.action.TAG_DISCOVERED is only used for fall-back tag detection. All three NFC intents (NDEF_DISCOVERED, TECH_DISCOVERED, TAG_DISCOVERED) have three extras: android.nfc.extra.ID: This is the UID (or whatever it's equivalent is called for that technology). android.nfc.extra.NDEF_MESSAGES: If the tag is an NDEF tag (or a dummy tag for NPP) this extra contains the received NDEF messages. android.nfc.extra.TAG: This is the Tag object for the detected tag. You can use it to get the tags technology and to create technology specific connections. br, Michael -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
