Java : GUIs and Event Driven Programming

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Java GUIs and Event Driven Programming

• Review notes, Module 10

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10.1.1 Event driven programming

• The Java language uses an event delegation model
  to handle events.
• A source of an event This is an object that can
  generate an event object.
• The event This is an event object that
  encapsulates information about the event.
• The handler This is the object that can handle
  the event, which is performing some task.

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10.1.1 Event driven programming

• The code that the programmer will write to
  implement the event driven model consists of
  three steps.
• These are creating a event source, such as a GUI
  component,
• creating an instance of an object that implements
  the appropriate event listener interface,
• and then connecting (registering) the listener
  object to the source object.

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10.1.2 Event objects
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10.1.4 Adapter classes

• The adapter classes have the name of the Listener
  interface and the word Adapter. They are
  implemented as part of the java.awt.events
  package.

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10.2.1 Inner classes

• Anonymous classes are an alternative form of
  instance class creation.
• An inner class is located in a .java file that
  matches the new class.

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10.4.1 Applets and event-driven programming

• The code in this method uses the getSource()
  method of the ActionEvent object to determine
  which object generated the event and the action
  to be performed.

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Extra

• The primary reason to construct custom exception
  is because it allows the programmer to tailor a
  handler to manage a specific exceptional problem
  that the enclosing method may encounter.
• A key step in creating a custom checked exception
  handler is to subclass the custom class from
  class Exception .

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Extra

• The instructions that could be used in an
  actionPerformed method to differentiate between
  buttons buttonOne and buttonTwoif (
  e.getSource() btnOne )txtOne( "First button"
  )else if ( e.getSource() btnTwo )txtOne(
  "Second button" )