Java is a general purpose object-oriented programming language based on several already popular and familiar languages.
Java programs (bytecode) are run (or interpreted) by another program called the Java Virtual Machine (Java VM).
Java programs are case sensitive,
Compiler
javac.exe - located in jdk1.4 bin\ on my machine
javac used to compile both programs and applets.
The system references the CLASSPATH environment variable to see where it should look for classes to be run.
In Windows98 or WindowNT use 'SET' at the DOS prompt to see current CLASSPATH setting.
private
No other class can instantiate your class. Your class may contain public class methods (sometimes called factory methods), and those methods can construct an object and return it, but no other classes can.
protected
Only subclasses of the class and classes in the same package can create instances of it.
public
Any class can create an instance of your class.
no specifier gives package access
Only classes within the same package as your class can construct an instance of it.
Applets do not have a main method as an entry point, but instead, have
several methods to control specific aspects of applet execution.
To create an applet, you extend (or subclass) the Applet class and implement the appearance and behavior you want.
The Applet class provides the init, start, stop, destroy, and paint methods
you saw in the example applet. The SimpleApplet class overrides these
methods to do what the SimpleApplet class needs them to do. The Applet
class provides no functionality for these methods.
Applications of any size and all applets use import statements to access ready-made Java API classes in packages.