Threads - Beginning Java - page 751

In any case, it is not important to understand exactly how this works. Just remember: Always start your
thread by calling the start() method. If you call the run() method directly, you have not created a new
thread and your program does not work as you intended.
You can define a class that is to represent a thread in two ways:
• You can define a subclass of Thread that provides a definition of the run() method that overrides
the inherited method.
• You can define your class as implementing the Runnable interface, which declares the run()
method, and then creates a Thread object in your class when you need it.
You explore the advantages of both approaches in a little more detail. You can see how deriving a subclass
of Thread works by using an example.

TRY IT OUT: Deriving a Subclass of Thread
You define a single class, TryThread , which you derive from Thread . As always, execution of the ap-
plication starts in the main() method. Here's the code:

import java.io.IOException;

public class TryThread extends Thread {
public TryThread(String firstName, String secondName, long delay) {
this.firstName = firstName; // Store

the first name
this.secondName = secondName; // Store the

second name
aWhile = delay; // Store the

delay
setDaemon(true); // Thread is

daemon
}

public static void main(String[] args) {
// Create three threads
Thread first = new TryThread("Hopalong ", "Cassidy ", 200L);
Thread second = new TryThread("Marilyn ", "Monroe ", 300L);
Thread third = new TryThread("Slim ", "Pickens ", 500L);

System.out.println("Press Enter when you have had enough...\n");
first.start(); // Start

the first thread
second.start(); // Start the

second thread
third.start(); // Start the

third thread

try {
System.in.read(); // Wait