How can I interrupt a ServerSocket accept() method?

You can call close() from another thread, and the accept() call will throw a SocketException.

You can just create "void" socket for break serversocket.accept()

Server side

private static final byte END_WAITING = 66;
private static final byte CONNECT_REQUEST = 1;

while (true) {
      Socket clientSock = serverSocket.accept();
      int code = clientSock.getInputStream().read();
      if (code == END_WAITING
           /*&& clientSock.getInetAddress().getHostAddress().equals(myIp)*/) {
             // End waiting clients code detected
             break;
       } else if (code == CONNECT_REQUEST) { // other action
           // ...
       }
  }

Method for break server cycle

void acceptClients() {
     try {
          Socket s = new Socket(myIp, PORT);
          s.getOutputStream().write(END_WAITING);
          s.getOutputStream().flush();
          s.close();
     } catch (IOException e) {
     }
}

Is calling close() on the ServerSocket an option?

http://java.sun.com/j2se/6/docs/api/java/net/ServerSocket.html#close%28%29

Closes this socket. Any thread currently blocked in accept() will throw a SocketException.

Set timeout on accept(), then the call will timeout the blocking after specified time:

http://docs.oracle.com/javase/7/docs/api/java/net/SocketOptions.html#SO_TIMEOUT

Set a timeout on blocking Socket operations:

ServerSocket.accept();
SocketInputStream.read();
DatagramSocket.receive();

The option must be set prior to entering a blocking operation to take effect. If the timeout expires and the operation would continue to block, java.io.InterruptedIOException is raised. The Socket is not closed in this case.