/* EMERGENCY ROOM */ /* A Hospital Simulation */ /* featuring PriorityBlockingQueue */ /* written by Tibor Santa */ import java.util.concurrent.BlockingQueue; import java.util.concurrent.PriorityBlockingQueue; import java.util.List; import java.util.Random; public class Hospital { public static void main(String[] args) { System.out.println("A new day begins at the hospital!\n"); BlockingQueue sharedQueue = new PriorityBlockingQueue<>(); for (String clerk : List.of("Pam Beesley", "Ms Blankenship", "Andy Sachs")) { new Thread(new ReceptionDesk(sharedQueue, clerk)).start(); } for (String doc : List.of("Dr House", "Dr Brinkmann", "Dr Mengele")) { new Thread(new EmergencyRoom(sharedQueue, doc)).start(); } } } /** * Emergency Severity Index * @url https://en.wikipedia.org/wiki/Emergency_Severity_Index */ enum Severity { RESUSCITATION, EMERGENT, URGENT, LESS_URGENT, NONURGENT; private static final Severity[] VALUES = values(); private static final int SIZE = VALUES.length; private static final Random RANDOM = new Random(); public static Severity getRandomSeverity() { return VALUES[RANDOM.nextInt(SIZE)]; } } class Patient implements Comparable { private Severity severity; private int ticket; public Patient(Severity severity, int ticket) { this.severity = severity; this.ticket = ticket; } @Override public int compareTo(Patient other) { return this.severity.ordinal() - other.severity.ordinal(); } @Override public String toString() { return "Patient " + this.ticket + " (" + this.severity + ")"; } } class ReceptionDesk implements Runnable { private static int ticket = 101; private String clerk; private BlockingQueue sharedQueue; public ReceptionDesk(BlockingQueue queue, String clerk) { this.sharedQueue = queue; this.clerk = clerk; } @Override public void run() { System.out.println("[Desk] Receptionist " + this.clerk + " starts her shift."); while (ticket <= 140) { registerNextPatient(Severity.getRandomSeverity()); } System.out.println("[Desk] " + this.clerk + " closes her desk."); } private void registerNextPatient(Severity severity) { try { Patient patient = new Patient(severity, ticket++); System.out.println(">> " + this.clerk + " registered " + patient); sharedQueue.put(patient); Thread.sleep((int) (Math.random() * 40)); } catch (InterruptedException e) { e.printStackTrace(); } } } class EmergencyRoom implements Runnable { private BlockingQueue sharedQueue; private String doctor; public EmergencyRoom(BlockingQueue queue, String doctor) { this.sharedQueue = queue; this.doctor = doctor; } @Override public void run() { try { Thread.sleep(80); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("[ER] " + this.doctor + " starts seeing patients."); while (!sharedQueue.isEmpty()) { treatNextPatient(); } System.out.println("[ER] " + this.doctor + " finished work."); } private void treatNextPatient() { try { Patient patient = sharedQueue.take(); System.out.println("<< " + this.doctor + " treated " + patient); Thread.sleep((int) (Math.random() * 70)); } catch (InterruptedException e) { e.printStackTrace(); } } }

Emergency Room