JAVA Events and Types of Events in Detail
- Every event is a unique occurrence at a point in time.
- It causes transitions between states.
- Events might be related or unrelated. If two events are casually unrelated they are said to be concurrent.
- The event often corresponds to verb in past tense. i.e. door_opened, door_closed event.
- An event happens instantaneously with regard to the timescale of an application.
- It is simply an occurrence that application considers as atomic and short-lived.
- Events include error conditions like motor jammed, transaction aborted, and timeout, etc.
- In software modeling system we do not try to establish an ordering between concurrent events because they can occur in any order.
- The most common type of events is the signal event, the change event, and the time event.
Grouping every JAVA events into event classes and gives each java events class a name to indicate common structure and behavior is known as Signal Event.
It is a one-way transmission of information from one object to another. It is the event of sending or receiving signal.
The UML notation is the keyword signal in guillemets (<< >>) above the signal class name in the top section of a box.
The difference between signal and signal event is :
- Signal: one-way transmission between object.
- Signal event: an occurrence in time.
- The change java events caused by the satisfaction of Boolean expression. Whenever the expression changes from false to true the event happens.
- The UML notation for a change event is the keyword when followed by a parenthesized Boolean expression.
- A time event an event caused by the occurrence of an absolute time or the elapse of a time interval.
- The UML notation for an absolute time is the keyword when followed by a parenthesized expression involving time.
- This event caused by the occurrence of an absolute time or the elapsed of a time interval.
- The notation for a time interval is the keyword after followed by a parenthesized expression that evaluates to the time duration.