A Brief insight into The Java 1.0 Event Model

Gopalan Suresh Raj

The Java 1.0 Event Model was based on Inheritance. It was thus called the Java 1.0 Inheritance Event Model. A program that needed to process GUI events was required to subclass GUI components and override either the action() or handleEvent() methods.

Returning "true" from one of these subclassed methods consumed the event so the event was not propagated furthur up the heirarchy. Otherwise the event was propagated sequentially up the GUI hierarchy until it was either consumed or the root of the hierarchy was reached. Programs thus had two ways to structure their event-handling code:

	Either individual components could be subclassed to specifically handle their target events or,
	All events for an entire hierarchy could be handled by a particular container.

Thus there was no filtering of events. Events were always delivered to components regardless of whether the components actually required or handled them or not. This was considered a severe performance problem.