Make sure you have enabled android beam in options. The other device that will receive the file also have to use android beam or something similar.
If u want to send a single file then open it in album on full screen and then stick the devices together.
On a side note - NFC is useless for sending files. The actual file transfer goes over Bluetooth so all it does is just pairing the devices for you. Not worth the hassle imo...
What really grind my gears is why the hell aren't files being sent over WiFi direct... That would send the files MUCH faster and would make NFC useful for sending a lot of data. At this point? Don't even bother if it's just a test.
If you really want to try then open some page in chrome on your device and stick it to another. It should also send the website adress to the other device.
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