Java Server for Basic Arithmetic Operations

The assignment is to create a Java program that acts as a simple calculator server, accepting requests from clients and performing basic arithmetic operations (addition, subtraction, multiplication, division) on the operands provided in the request. The server continuously accepts requests until it receives an 'EXIT' command, at which point it shuts down.

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package test;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
/**
* Support add, subtraction, multiplication, division
* @author hluu
*
*/
public class MyServer {
enum OPERATOR { ADD, SUB, MULT, DIV };
public static final int PORT_NO = 12345;
/**
* @param args
* @throws IOException
* @throws InterruptedException
*/
public static void main(String[] args) throws IOException, InterruptedException {
ServerSocket serverSocket = new ServerSocket(PORT_NO);
System.out.println("... server is accepting request");
while (true) {

Socket socket = serverSocket.accept();
BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String line = reader.readLine();
if (line.trim().startsWith("EXIT")) {
System.out.println("... server shutting down ...");
socket.close();
break;
} else {
System.out.println("Got Request " + line);
processRequest(socket, line);
}
}
System.out.println("... closing server socket ...");
serverSocket.close();
}
private static void processRequest(Socket socket, String line) throws IOException, InterruptedException {
PrintWriter pw = new PrintWriter(socket.getOutputStream());
String[] tokens = line.split(" ");
String operator = tokens[0].trim();
try {
Double operand1 = Double.valueOf(tokens[1].trim());
Double operand2 = Double.valueOf(tokens[2].trim());
System.out.println(operand1);System.out.println(operand2);

double result = 0;
OPERATOR op = OPERATOR.valueOf(operator.toUpperCase());
switch (op) {
case ADD:
result = operand1 + operand2;
break;
case SUB:
result = operand1 - operand2;
break;
case MULT:
result = operand1 * operand2;
break;
case DIV:
result = operand1 / operand2;
break;
default:
pw.println("invalid operand: " + line);
pw.flush();
socket.close();
return;
}
System.out.println("Response: " + result );
pw.println(result);
} catch (NumberFormatException e) {
pw.println("invalid operand: " + line);
}
pw.flush();
socket.close();
}
}