title: Unfortunately app has stopped Android emulator
body: <p>I'm new to Android programming. I'm getting crazy with this problem.
  I'm trying to create a client/server communication with a simple code from this link:
  <a href="http://lakjeewa.blogspot.it/2012/03/simple-client-server-application-for.html" rel="nofollow">http://lakjeewa.blogspot.it/2012/03/simple-client-server-application-for.html</a>
  when i run the "SimpleClientActivity" app on the emulator, it works, but when i press the button, the message "unfortunately, the app has stopped" appears and the app closes.</p>
  
  <p>the Main.java (Server side) works fine.</p>
  
  <p>What can be the problem?</p>
  
  <p>Thank you everybody in advance!</p>