user16885: I am developing JSP web. User will be redirected to another page only if he sends the certain amount of BTC, is there any listener which could check if money arrived to my wallet from the certain wallet address? 
And after leaving the page is there possibility to automatically send the money back to the user?
Maybe some good tutorial on bitcoinj or something? Any suggestions?

user15524: I would suggest using a Web API to get notified when a transaction happens on the address(es) you're interested in, it's by far the simpler. Something like this may help:
http://dev.blockcypher.com/#websocket_webhook

user11013: for small amounts 6 confirmations are overkill, you could just listen for the payment to be relayed by some bitcoin nodes which happens in seconds. 
For your question, clone bitcoinj and look at the examples (more specifically the 'Kit' example). Use that as a basis and then read the chapter on 'Watching Wallets' in the docs:
https://bitcoinj.github.io/working-with-the-wallet
You can specify a listener which is called when there's activity on your address/wallet.

16885: <p>I am developing JSP web. User will be redirected to another page only if he sends the certain amount of BTC, is there any listener which could check if money arrived to my wallet from the certain wallet address? 
And after leaving the page is there possibility to automatically send the money back to the user?</p>

<p>Maybe some good tutorial on bitcoinj or something? Any suggestions?</p>
 15524: <p>I would suggest using a Web API to get notified when a transaction happens on the address(es) you're interested in, it's by far the simpler. Something like this may help:</p>

<p><a href="http://dev.blockcypher.com/#websocket_webhook" rel="nofollow">http://dev.blockcypher.com/#websocket_webhook</a></p>
 11013: <p>for small amounts 6 confirmations are overkill, you could just listen for the payment to be relayed by some bitcoin nodes which happens in seconds. </p>

<p>For your question, clone bitcoinj and look at the examples (more specifically the 'Kit' example). Use that as a basis and then read the chapter on 'Watching Wallets' in the docs:
<a href="https://bitcoinj.github.io/working-with-the-wallet" rel="nofollow">https://bitcoinj.github.io/working-with-the-wallet</a></p>

<p>You can specify a listener which is called when there's activity on your address/wallet.</p>
