NFC Android

bnogal

I have been for a week trying to use the NFC in android.

3 years ago i implemented a tag transmitter for a mime tag using JNI, with the same mobiles i am using now.

I dont wanna reuse that old code, as i modified the android.java, and i dont wanna reinvent the wheel for each platform Qt "gives" support for NFC

Why there is a QNearFieldShareManager? Why not just QNearFieldManager
When signal for a QNearFieldTarget detected is received, i run this:```


           qDebug() << "Target detected to read messages "<<target <<" "<<m_target->hasNdefMessage();
            connect(target,&QNearFieldTarget::ndefMessageRead,this,&NFCReader::readMessage, Qt::UniqueConnection);
            connect(target,&QNearFieldTarget::requestCompleted,this,&NFCHelper::processRequestCompleted, Qt::UniqueConnection);
            connect(target,&QNearFieldTarget::error,this,&NFCHelper::error, Qt::UniqueConnection);
            QNearFieldTarget::RequestId id = target->readNdefMessages();
            qDebug() << "VALID "<<id.isValid();```

VALID returns true, but i get signal error, with error : QNearFieldTarget::Error(TargetOutOfRangeError)

between "Target detected to read messages NearFieldTarget(0x5d35d620) true" and the VALID trace i get:

W/System.err(27837): java.lang.NullPointerException
W/System.err(27837): 	at android.nfc.tech.BasicTagTechnology.connect(BasicTagTechnology.java:73)
W/System.err(27837): 	at android.nfc.tech.Ndef.connect(Ndef.java:76)
W/System.err(27837): 	at dalvik.system.NativeStart.run(Native Method)

The device sending the message, dont show any trace..? no QNearFieldTarget detected , so who is sending it, and what?
If application is closed, when i receive the message it opens, as it is registered in the AndroidManifest

I tryed using QNearFieldShareManager and QNearFieldManager directly

bnogal

After another 6 hours

Now i get the events of target detected in the writter
but still i get the same errors.

But I give up. If someone ask me, i will say Qt dont support NFC in android, because this should be easy.

jsulm

@bnogal Did you check https://doc.qt.io/qt-5/nfc-android.html ?

bnogal

@jsulm Thx for a reply in this desperating thing...
I checked that page already (a bit hidden by the way). It is registered and the application get launched on tag detection, but i don't receive the data because the QNearFieldTarget::Error(TargetOutOfRangeError) probability related to the null pointer exception in java.

i wonder if it could be related to https://bugreports.qt.io/browse/QTBUG-59343