Add OOP/Java/Assignments/FISAC/Q9.java

OOP/Java/Assignments/FISAC/Q9.java

@@ -0,0 +1,40 @@
+import java.util.concurrent.*;
+import java.util.*;
+
+class SeatAlreadyBookedException extends Exception {
+    SeatAlreadyBookedException(String msg) { super(msg); }
+}
+
+public class SeminarHall {
+    static final int TOTAL_SEATS = 15;
+    static Map<Integer, String> seats = new ConcurrentHashMap<>();
+
+    public static void main(String[] args) {
+        ExecutorService executor = Executors.newFixedThreadPool(20);
+        for (int i = 1; i <= 15; i++) seats.put(i, "Available");
+        for (int i = 0; i < 20; i++) {
+            int userId = i;
+            executor.submit(() -> {
+                try {
+                    bookSeat(userId, "User" + userId, "Aadhar" + userId);
+                } catch (SeatAlreadyBookedException e) {
+                    System.out.println(e.getMessage());
+                }
+            });
+        }
+        executor.shutdown();
+        try { executor.awaitTermination(1, TimeUnit.MINUTES); } catch (InterruptedException e) {}
+        System.out.println("Final Booking Status: " + seats);
+    }
+
+    static void bookSeat(int userId, String name, String aadhar) throws SeatAlreadyBookedException {
+        int seatNumber = (userId % TOTAL_SEATS) + 1;
+        synchronized (seats) {
+            if (!seats.get(seatNumber).equals("Available")) {
+                throw new SeatAlreadyBookedException("Seat " + seatNumber + " already booked by another user.");
+            }
+            seats.put(seatNumber, name + " (" + aadhar + ")");
+            System.out.println("Seat " + seatNumber + " booked by " + name);
+        }
+    }
+}