Server-client program using Java socket

public class Server {
    public static void main(String[] args) {
        try {
            ServerSocket serverSocket = new ServerSocket(7777);
            while(true) {
            Socket socket = serverSocket.accept();
            BufferedReader si=new BufferedReader(new InputStreamReader(socket.getInputStream(), "UTF-8"));
            PrintWriter so= new PrintWriter(new OutputStreamWriter(socket.getOutputStream(),"UTF-8"));

            if(si.readLine()=="A"){
                so.println(getDirContent());

            } } else {
                so.println(si.readLine());
            }
             so.flush(); si.close(); so.close(); socket.close();
            }
        } } catch(Exception e) {}

    }
    private static String getDirContent() {
        File dir=new File("C:/");
        String files[]=dir.list();
        List<String> list=Arrays.asList(files);
        return list.toString();
    }

}

public class Client {
    public static void main(String[] args) {
        try {
            Socket socket=new Socket("localhost",7777);
            BufferedReader si=new BufferedReader(new InputStreamReader(socket.getInputStream(),"UTF-8"));
            PrintWriter so=new PrintWriter(new OutputStreamWriter(socket.getOutputStream(),"UTF-8"));
            Scanner ki=new Scanner(System.in);
            so.println(ki.nextLine()); so.flush();
            System.out.println(si.readLine());
            si.close(); so.close(); ki.close(); socket.close();
        } } catch(Exception e) {
            System.out.println(e.getMessage());
        }
    }

}