Questions with java socket

In java, I can write code like this:

 ServerSocket ss = new ServerSocket(开发者_StackOverflow社区1111);
 Socket s = ss.accept();
 // here s.getLocalPort() is 1111
 ss.close();
 // here this is ok even s is still connected with a client.
 ss = new ServerSocket(s.getLocalPort());

on client side:

Socket s = new Socket("localhost", 1111);
// this line will throw an exception. 
ServerSocket ss = new ServerSocket(s.getLocalPort());

What I don't understand is the last line of the above two pieces of code seems no difference, why does it work differently? any info is highly appreciated, thank you in advance.

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In the first case you closed the socket, in the second you didn't, so the port is still occupied.