Threads - JavaTech: An Introduction to Scientific and Technical Computing with Java - page 257

g.drawString ( " Thread demo 2 " ,20,20);
}
} // class MyRunnableApplet
The diagram in Figure 8.2 shows schematically how this approach works.
8.2.3 Thread subclass vs. Runnable
The choice between these two thread creation techniques depends on the particular
application and what seems most appropriate and convenient for it. Since Java
does not allow multiple inheritance, an applet class that is already a subclass of
Applet or JApplet can become multithreaded by implementing Runnable .
The run() method will have access to the variables and methods of the class.
Forexample, an applet animation may need parameters for initialization and may
also need to invoke methods from the applet.
Extending Thread applies well to the situation where you want to create a
specialized thread class that does not need to extend any other class. A common
case is where many worker threads are needed such as in a server program that
Figure 8.2 This diagram illustrates threading with a Runnable class.
MyRunnableApplet implements the Runnable interface and it creates an instance of
Thread and passes in the constructor a reference to itself as a Runnable object. (We
use the name “ runnable ” for the reference variable to the Runnable object.) The
applet invokes the start() method for the thread and it returns while the thread
process continues independently with the invocation of the run() method in the
applet object. When the thread process returns from the applet's run() the thread
dies.