Summary of Class Presentation for June 9, 1999

	We started by discussing the two different ways in which
applications and applets are developed.  If you download and install the
Sun Java SDK as specified in the readme file that is part of the 
download, you follow these steps for applications:
	1.  Use a text editor to enter the program text as one or more
		text-only files.  These files must be named for the 
		public class each contains with extension .java
	2.  Invoke javac from the MS-DOS command prompt to compile the
		.java files into bytecode files (one for each class)
		into .class files.
	3.  Execute the .class files using the java command to invoke the
		Java runtime interpreter that interprets the bytecodes.
Of course, if you downloaded and installed one of the three shareware 
integrated development environments mentioned in the course 
syllabus, that 
environment has commands to handle all of this. 

	For applets the procedure is different:
	1.  Use a text editor to enter the program text as one or more
		text-only files.  These files must be named for the 
		public class each contains with extension .java.
	2.  Use javac as above to compile into .class files.
	3.  Write an html description for the web page that will contain'
		the applet using the <applet> html command.
	4.  Load the web page into a browser.  The browser will 
		load and start the applet as it interprets the html.

	Differences between applets and applications:
	1.  applications have a main method within a public class.  This
		is where execution begins.  applets use an API 
		(application programming interface) to interact with the
		browser:
		a.  init() called by browser when the applet is first
		loaded into memory
		b.  start() called by the browser whenever the web page
		containing the applet becomes the top web page
		c.  stop() called by the browser whenever the web page
		containing the applet stops being the top web page
		d.  destroy() called by the browser just before the 
		browser terminates execution normally.
		e.  paint( Graphics g ) called indirectly by the browser whenever
		the page portion controlled by the applet must be 
		redrawn.   Can be called by applet code to force a redraw
	2.  applications can access any files, web sites, or databases 
		accessible to their user.  Applets execute in a sandbox 
		that restricts their access to ensure that untrusted 
		applets cannot modify or affect other software.
	3.  applets extend (inherit from) the class applet.  Application
		classes do not explicitly extend any other classes unless
		the writer needs them to.

We examined several example programs, both applications and applets 
together with the needed HTML code to use an applet.