This abstract class provides event scheduling tools. More...

Inheritance diagram for Event:

Collaboration diagram for Event:

Public Member Functions
final int	getRa ()

final void	setRa (int r)

	Event ()
	Constructs a new event instance, which can be placed afterwards into the event list of the default simulator by calling one of the `schedule...` variants. More...

	Event (Simulator sim)
	Construct a new event instance associated with the given simulator. More...

void	schedule (double delay)
	Schedules this event to happen in `delay` time units, i.e., at time `sim.time() + delay`, by inserting it in the event list. More...

void	scheduleNext ()
	Schedules this event as the first event in the event list, to be executed at the current time (as the next event).

void	scheduleBefore (Event other)
	Schedules this event to happen just before, and at the same time, as the event `other`. More...

void	scheduleAfter (Event other)
	Schedules this event to happen just after, and at the same time, as the event `other`. More...

void	reschedule (double delay)
	Cancels this event and reschedules it to happen in `delay` time units. More...

boolean	cancel ()
	Cancels this event before it occurs. More...

final boolean	cancel (String type)
	Finds the first occurence of an event of class "type" in the event list, and cancels it. More...

final Simulator	simulator ()
	Returns the simulator linked to this event. More...

final void	setSimulator (Simulator sim)
	Sets the simulator associated with this event to `sim`. More...

final double	time ()
	Returns the (planned) time of occurence of this event. More...

final void	setTime (double time)
	Sets the (planned) time of occurence of this event to `time`. More...

final double	priority ()
	Returns the priority of this event. More...

final void	setPriority (double priority)
	Sets the priority of this event to `inPriority`. More...

int	compareTo (Event e)
	Compares this object with the specified object `e` for order. More...

abstract void	actions ()
	This is the method that is executed when this event occurs. More...

Protected Attributes
Simulator	sim

double	priority

double	eventTime

Detailed Description

This abstract class provides event scheduling tools.

Each type of event should be defined as a subclass of the class Event, and should provide an implementation of the method actions which is executed when an event of this type occurs. The instances of these subclasses are the actual events.

Each event is linked to a simulator represented by an instance of Simulator before it can be scheduled and processed. A default simulator, given by Simulator.getDefaultSimulator, is used if no simulator is linked explicitly with an event. When an event is constructed, it is not scheduled. It must be scheduled separately by calling one of the scheduling methods schedule, scheduleNext, scheduleBefore, etc. An event can also be cancelled before it occurs.

A scheduled event has an associated time at which it will happen and a priority, which can be queried using the methods time and #priority, respectively. By default, events occur in ascending order of time, and have priority 1. Events with the same time occur in ascending order of priority. For example, if events e1 and e2 occur at the same time with priority 2 and 1 respectively, then e2 will occur before e1. Events with the same time and priority occur in the order they were scheduled.

Constructor & Destructor Documentation

◆ Event() [1/2]

Event ( )

Constructs a new event instance, which can be placed afterwards into the event list of the default simulator by calling one of the schedule... variants.

For example, if Bang is an Event subclass, the statement "<tt>new Bang().scheduleNext();</tt>" creates a new Bang event and places it at the beginning of the event list.

   public Event (double delay) \begin{hide} {
      this (Simulator.getDefaultSimulator(), delay);
   } \end{hide}
   public Event (Simulator sim, double delay)\begin{hide} {
      if (sim == null)
         throw new NullPointerException();
      if (delay >= 0.0) {
         priority = 1;
         this.sim = sim;
         eventTime = sim.time() + delay;
         sim.eventList.add (this);
      }
      else
         throw new IllegalArgumentException ("Cannot schedule in the
past.");
   }\end{hide}

Constructs a new event and inserts it in the event list of the default simulator. If delay >= 0.0, the event is scheduled to happen in delay units of simutated time. If two or more events are scheduled to happen at the same time, events with the highest priorities (lowest value of the priority field) occur first. If two or more events are schedule to the same time, with the same priority, they are placed in the event list (and executed) in the same order as they have been scheduled.

We recall that such constructors with parameters are not inherited automatically by the subclasses in Java, but they can be invoked using super. For example, one can have

class Bang extends Event {
   public Bang (double delay) { super (delay); }
   public void actions() {  \dots  }

and then invoke the constructor "<tt>new Bang (10.0)</tt>" to get a Bang in 10 units of time. This is equivalent to "<tt>new Bang().schedule(10.0)</tt>."

Parameters

delay simulation time that must pass before the event happens

◆ Event() [2/2]

Event ( Simulator sim )

Construct a new event instance associated with the given simulator.

Parameters

sim	Instance of class Simulator associated with the new Event

Member Function Documentation

◆ actions()

abstract void actions ( )

abstract

This is the method that is executed when this event occurs.

Every subclass of Event that is to be instantiated must provide an implementation of this method.

◆ cancel() [1/2]

boolean cancel ( )

Cancels this event before it occurs.

Returns true if cancellation succeeds (this event was found in the event list), false otherwise.

Returns: true if the event could be cancelled

◆ cancel() [2/2]

final boolean cancel ( String type )

Finds the first occurence of an event of class "type" in the event list, and cancels it.

Returns true if cancellation succeeds, false otherwise.

Parameters

type	name of an event subclass

Returns: true if an event of this class was found and cancelled

◆ compareTo()

int compareTo ( Event e )

Compares this object with the specified object e for order.

Returns \(-1\) or \(+1\) as this event occurs before or after the specified event e, respectively. If the two events occur at the same time, then returns \(-1\), \(0\), or \(+1\) as this event has a smaller, equal, or larger priority than event e.

◆ priority()

final double priority ( )

Returns the priority of this event.

Returns: the priority of the event

◆ reschedule()

void reschedule ( double delay )

Cancels this event and reschedules it to happen in delay time units.

Parameters

delay simulation time units that must elapse before the event happens

◆ schedule()

void schedule ( double delay )

Schedules this event to happen in delay time units, i.e., at time sim.time() + delay, by inserting it in the event list.

When two or more events are scheduled to happen at the same time and with the same priority, they are placed in the event list (and executed) in the same order as they have been scheduled. Note that the priority of this event should be adjusted using setPriority before it is scheduled.

Parameters

delay simulation time that must pass before the event happens

◆ scheduleAfter()

void scheduleAfter ( Event other )

Schedules this event to happen just after, and at the same time, as the event other.

Parameters

other event after which this event will be scheduled

◆ scheduleBefore()

void scheduleBefore ( Event other )

Schedules this event to happen just before, and at the same time, as the event other.

For example, if Bing and Bang are Event subclasses, after the statements

Bang bigOne = new Bang().schedule(12.0);

new Bing().scheduleBefore(bigOne);

the event list contains two new events scheduled to happen in 12 units of time: a Bing event, followed by a Bang called bigOne.

Parameters

other event before which this event will be scheduled

◆ setPriority()

final void setPriority ( double priority )

Sets the priority of this event to inPriority.

This method should never be called after the event was scheduled, otherwise the events would not execute in ascending priority order anymore.

Parameters

priority new priority for the event

◆ setSimulator()

final void setSimulator ( Simulator sim )

Sets the simulator associated with this event to sim.

This method should not be called while this event is in an event list.

Parameters

sim	the Simulator

◆ setTime()

final void setTime ( double time )

Sets the (planned) time of occurence of this event to time.

This method should never be called after the event was scheduled, otherwise the events would not execute in ascending time order anymore.

Parameters

time	new time of occurence for the event

◆ simulator()

final Simulator simulator ( )

Returns the simulator linked to this event.

Returns: the simulator linked to the event

◆ time()

final double time ( )

Returns the (planned) time of occurence of this event.

Returns: the time of occurence of the event

The documentation for this class was generated from the following file:

Event.java

Public Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ Event() [1/2]

◆ Event() [2/2]

Member Function Documentation

◆ actions()

◆ cancel() [1/2]

◆ cancel() [2/2]

◆ compareTo()

◆ priority()

◆ reschedule()

◆ schedule()

◆ scheduleAfter()

◆ scheduleBefore()

◆ setPriority()

◆ setSimulator()

◆ setTime()

◆ simulator()

◆ time()