Send NFC tag in Android if app isn't open?

It's possible to send any string by NFC in Android if i dont have any application open to make it?

Imagine you pass the smartphone in passive mod开发者_StackOverflow社区e on a reader NFC. Can reader receveive any data if i dont have a application on the smartphone side to send it?

In short, no, at least not through SDK API's.

There are no NFC Card Emulation SDK API's.

Peer-to-peer would also work, but these API's only allow a foreground Activity to send a message. This is by design.

The basic reason is to keep privacy simple for the user, we talk about this in more detail in our "How to NFC" talk: http://www.youtube.com/watch?v=49L7z3rxz4Q

Card emulation it's not yet public in the sdk. Read here paragraph Card Emulation, but maybe there is a way as you can read in the blog.