Why do I get an exception during wifi direct socket connection?

Question

I got a exception when I run that code on my android server device but I don't understand why, can you please help me.

WifiP2pDevice peer = wifiP2pDeviceList.getDeviceList().iterator().next();
String host = peer.deviceAddress;
ServerSocket serverSocket = new ServerSocket(2009);
Socket client = serverSocket.accept(); // I got the exception here

Exception : FATAL EXCEPTION: main android.os.NetworkOnMainThreadException

Answer 1

Android recognizes a network call as potentially non-responsive, so it prevents you from doing this on the UI thread. You need to make the call in AsyncTask or in a background process. See this:

http://www.vogella.com/tutorials/AndroidBackgroundProcessing/article.html

And additional (popular) explanation of the error:

How to fix android.os.NetworkOnMainThreadException?

Answer 2

That's because networking related stuff is not allowed in UI thread but there's a workaround, just add these lines in your onCreate, below the setContentView(to avoid any mistakes :) )

StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);

But it would be a good practice if you do it on a Non-UI thread.