feat: add Lab4

Lab1/ServiceBeginEvent.java

@@ -0,0 +1,34 @@
+/**
+ * The ServiceBeginEvent is an Event which handles the starting of a service.
+ * It handles occupying a counter and also generating a serviceEndEvent
+ * 
+ * @author Yadunand Prem
+ * @version CS2030S AY22/23 Semester 2
+ */
+class ServiceBeginEvent extends Event {
+
+  private ServiceCounter counter;
+  private Customer customer;
+  private Shop shop;
+
+  public ServiceBeginEvent(double time, Customer customer, Shop shop, ServiceCounter counter) {
+    super(time);
+    this.customer = customer;
+    this.shop = shop;
+    this.counter = counter;
+  }
+
+  @Override
+  public String toString() {
+    return super.toString()
+        + String.format(": %s service begin (by %s)", this.customer, this.counter);
+  }
+
+  @Override
+  public Event[] simulate() {
+    this.counter.occupy();
+    double endTime = this.getTime() + this.customer.getServiceTime();
+    return new Event[] {
+        new ServiceEndEvent(endTime, this.customer, this.shop, this.counter) };
+  }
+}