Introducing Applets and the Advanced Graphics and User Interface - Beginning Java ME Platform - page 251

The APPLET HTML tag specifies that the Java applet defined in the Java class file
HelloWorld.class should be loaded from the web server's applets directory and given the
name hello within the current applet's context.
Returning to the topic of interapplet communication, consider two applets: Producer
and Consumer . Producer provides an interface used by Consumer within the context of a sin-
gle execution environment such as a web page. Producer only needs to declare a method
to be used by Consumer , as shown in Listing 10-6.
Listing 10-6. Declaring a Method Used by Consumer in Producer
public class Producer extends Applet {
… methods here …
public void processRequest(String anArgument) {
… do something with anArgument …
}
}
The HTML that serves the Producer applet must identify Producer so that Consumer can
find it by name using the AppletContext , as shown in Listing 10-7.
Listing 10-7. Identifying the Producer Applet
<APPLET CODEBASE="applets/" CODE="Producer.class"
WIDTH=200
HEIGHT=200
NAME="producer"/>
The Consumer applet, which invokes Producer 's processRequest method, only needs to
locate the Producer in the applet context. It can then treat the resulting object like any
other Java object, invoking its processRequest method, as shown in Listing 10-8.
Listing 10-8. Invoking the Producer's processRequest Method
public class Consumer extends Applet
implements ActionListener {
… methods here …
public void actionPerformed(ActionEvent e) {
Applet producer = null;
producer = getAppletContext().getApplet("producer");
if (producer != null &&
producer instanceof Producer) {
((Producer)producer).processRequest("Hi!");