Document handling

Swing needs to respond some special types of events to handle text changes and formatting -- it does this with a class named Document.

Note: In the Swing MVC architecture, the Document class serves as a model.

It contains no capability for user interface.

These functions originate with the users of this class, such as JTextField and JTextArea.

The Document class:

• a Swing-based container used to hold text and to provide notification of changes to this text.
• implements support for mark-up (text selection)
• includes an internal structure to manage changes to its text.
• The structure of these elements consists of a base unit of containment called an element, each of which includes an arbitrary set of attributes associated with its text.
  • Root Element
  • Line/Paragraph Line/Paragraph
  • Content Element Break Content Element Break

• Typically, an instance of Document will contain only a single element structure, but the interface supports building any number of structural projections over the text element.
• Document supports multiple root elements and multiple data structures.
• For example, suppose you need to store modification notes or annotations along with the text.
  • you need to create an additional data structures associated with the annotations, in addition to structure that contains the actual text.