Polish

app/src/main/java/simulation/Event.java

@@ -1,8 +1,12 @@
 package simulation;
 
-class Event {
+class Event implements Comparable<Event> {
+	// Our only data members, we don't want anyone to tamper with these
+	private double eventTime;
+	private int eventType;
+
 	// Constructor, creates an event of a certain type that should be put in the
-	// event list at a certain time.
+	// event list at a certain time. Throws if type is out of bounds.
 	Event(int type, double eventTimeStamp) throws IllegalArgumentException {
 		if (type > 3 || type < 1)
 			throw new IllegalArgumentException("Event type must be one of ARRIVAL, READY or MEASURE");
@@ -11,11 +15,17 @@ class Event {
 		eventTime = eventTimeStamp;
 	}
 
-	// Empty constructor (used by the event list constructor)
-	// Event() {
-	// }
-
-	public double eventTime;
-	public int eventType;
-	public Event next = null; // Explicitly initialize to null
+	// Setters and getters for the private variables instead of having them public
+	public double getEventTime() {
+		return eventTime;
+	}
+	public int getEventType() {
+		return eventType;
+	}
+
+	// This is the custom comparator that PriorityQueue uses to sort the events
+	@Override
+	public int compareTo(Event e) {
+		return Double.compare(eventTime, e.eventTime);
+	}
 }

app/src/main/java/simulation/EventList.java

@@ -1,72 +1,41 @@
 package simulation;
 
-import java.util.LinkedList;
+import java.util.PriorityQueue;
 
-// Essentially a linked list of a non-template node type
+// Wrapper class for a priority queue of events
+// Changed from a linked list to a priority queue better suited for this type of application
 public class EventList {
-	private Event head = null;
-	private Integer size = 0;
 
-	EventList() {
+	// A heap backed, event containing priority queue.
+	private PriorityQueue<Event> pq = new PriorityQueue<>();
+	// This one contains events that are prioritized over the normal events
+	private PriorityQueue<Event> high_pq = new PriorityQueue<>();
+
+	// This is a helper function to get the correct queue
+	private PriorityQueue<Event> getQueue() {
+		return switch(high_pq.size()) {
+			case 0 -> pq; 		// If no priority events, return normal queue
+			default -> high_pq; // If priority events, return priority queue
+		};
 	}
 
-	// Yes
 	public Event getHead() {
-		return head;
+		return getQueue().peek();
 	}
 
 	public Integer length() {
-		return size;
+		return getQueue().size();
 	}
 
 	public void insertEvent(Event newEvent) {
-		if (this.head == null) {
-			this.head = newEvent;
-			size += 1;
-			return;
+		pq.add(newEvent);
 	}
 
-		Event cursor = this.head;
-		// int tries = 0;
-		// Find the right place in the list using a sliding window
-		while ((cursor.next != null) && (cursor.eventTime < newEvent.eventTime)) {
-			cursor = cursor.next;
-			// tries++;
-		}
-
-		if (cursor.eventTime > newEvent.eventTime) {
-			newEvent.next = this.head;
-			this.head = newEvent;
-		} else {
-			newEvent.next = cursor.next;
-			cursor.next = newEvent;
-		}
-
-		// System.out.println("Tries: " + tries);
-		size += 1;
+	public void insertPriorityEvent(Event newEvent) {
+		high_pq.add(newEvent);
 	}
 
 	public Event popEvent() {
-		if (head == null)
-			return null;
-		Event temp = head;
-		head = head.next;
-		temp.next = null;
-		size -= 1;
-		return temp;
+		return getQueue().poll();
 	}
-
-	public Event fetchEvent() {
-		Event temp = head.next;
-		head.next = temp.next;
-		temp.next = null;
-		size -= 1;
-		return temp;
-	}
-
-	// public Event popFront() {
-	// Event front = this.head;
-	// this.head = this.head.next;
-	// return front;
-	// }
 }

app/src/main/java/simulation/MainSimulation.java

@@ -12,9 +12,9 @@ public class MainSimulation extends GlobalSimulation {
 		myEventList.insertEvent(new Event(ARRIVAL, 0));
 		myEventList.insertEvent(new Event(MEASURE, 5));
 
-		while (MainSimulation.time < 50000) {
+		while (MainSimulation.time < 200000) {
 			actEvent = myEventList.popEvent();
-			MainSimulation.time = actEvent.eventTime;
+			MainSimulation.time = actEvent.getEventTime();
 			actState.TreatEvent(actEvent);
 		}
 

app/src/main/java/simulation/State.java

@@ -1,23 +1,22 @@
 package simulation;
 
-import java.util.*;
-
 class State extends GlobalSimulation {
 	public int numberInQueue = 0, accumulated = 0, noMeasurements = 0;
-	private EventList eventList;
+	private EventList eventList = null;
 
 	State(EventList eventList) {
 		this.eventList = eventList;
 	}
 
-	// Dispatches the events to the right handler
-	public void TreatEvent(Event x) {
-		if (x.eventType == ARRIVAL)
-			arrival();
-		else if (x.eventType == READY)
-			ready();
-		else if (x.eventType == MEASURE)
-			measure();
+	// Dispatches the events to the right handler with a java 20 switch statement
+	public void TreatEvent(Event event) {
+		switch (event.getEventType()) {
+			case ARRIVAL -> arrival();
+			case READY -> ready();
+			case MEASURE -> measure();
+		}
+		// System.out.println(String.format("Event type: %d, Customers: %d, Time: %.1f",
+		// event.getEventType(), numberInQueue, event.getEventTime()));
 	}
 
 	// Helper to generate a random number with certain statistical properties
@@ -28,8 +27,8 @@ class State extends GlobalSimulation {
 	private void arrival() {
 		if (numberInQueue == 0)
 			eventList.insertEvent(new Event(READY, time + generateMean(1)));
-		numberInQueue++;
 		eventList.insertEvent(new Event(ARRIVAL, time + generateMean(2)));
+		numberInQueue++;
 	}
 
 	private void ready() {

app/src/test/java/simulation/AppTest.java

@@ -1,12 +0,0 @@
-package simulation;
-
-// import org.junit.jupiter.api.Test;
-// import static org.junit.jupiter.api.Assertions.*;
-
-// No defined tests yet
-class AppTest {
-    // @Test void appHasAGreeting() {
-    //     App classUnderTest = new App();
-    //     assertNotNull(classUnderTest.getGreeting(), "app should have a greeting");
-    // }
-}

app/src/test/java/simulation/EventListTest.java

@@ -11,7 +11,6 @@ public class EventListTest {
         Event event = new Event(1, 0.0);
         eventList.insertEvent(event);
         assert eventList.getHead() == event;
-        assert eventList.getHead().next == null;
     }
 
     @Test
@@ -23,10 +22,10 @@ public class EventListTest {
         eventList.insertEvent(event3);
         eventList.insertEvent(event2);
         eventList.insertEvent(event1);
-        assert eventList.getHead() == event1;
-        assert eventList.getHead().next == event2;
-        assert eventList.getHead().next.next == event3;
-        assert eventList.getHead().next.next.next == null;
+        assert eventList.popEvent() == event1;
+        assert eventList.popEvent() == event2;
+        assert eventList.popEvent() == event3;
+        assert eventList.popEvent() == null;
     }
 
     @Test
@@ -55,9 +54,11 @@ public class EventListTest {
         for(int i : rand.ints(0, 100).limit(100).toArray()) {
             eventList.insertEvent(new Event(1, (double) i));
         }
+
+        Event prev = eventList.popEvent();
         for(Event e = eventList.getHead(); e != null; e = eventList.popEvent()) {
-            if(e.next == null) break;
-            assert e.eventTime < e.next.eventTime;
+            assert prev.getEventTime() <= e.getEventTime();
+            prev = e;
         }
     }
 }

app/src/test/java/simulation/EventTest.java

@@ -3,15 +3,10 @@ package simulation;
 import org.junit.jupiter.api.Test;
 
 public class EventTest {
-    @Test void testConstructor() {
+    @Test
+    void testConstructor() {
         Event event = new Event(1, 0.0);
-        assert event.eventType == 1;
-        assert event.eventTime == 0.0;
+        assert event.getEventType() == 1;
+        assert event.getEventTime() == 0.0;
     }
-
-    // @Test void testEmptyConstructor() {
-    //     Event event = new Event();
-    //     assert event.eventType == 0;
-    //     assert event.eventTime == 0.0;
-    // }
 }