— Scott McNealy, Sun Microsystems Chairman, President and ceo

Put your thread to sleep 
if you want to be sure 
that other threads get a 
chance to run. 
When the thread wakes 
up, it always goes back 
to the runnable state 
and waits for the thread 
scheduler to choose it 
to run again.

---

502
 
chapter 15
Using sleep to make our program 
more predictable.
Remember our earlier example that kept giving us different 
results each time we ran it? Look back and study the code 
and the sample output. Sometimes main had to wait until the 
new thread finished (and printed “top o’ the stack”), while 
other times the new thread would be sent back to runnable 
before it was finished, allowing the main thread to come back 
in and print out “back in main”. How can we fix that? Stop 
for a moment and answer this question: “Where can you put 
a sleep() call, to make sure that “back in main” always prints 
before “top o’ the stack”?
We’ll wait while you work out an answer (there’s more than 
one answer that would work).
Figure it out? 
public class MyRunnable implements Runnable {
public void run() {
go();
}
public void go() {
try {
Thread.sleep(2000);
} catch(InterruptedException ex) {
ex.printStackTrace();
}

doMore();
}
public void doMore() {
System.out.println(“top o’ the stack”);
}
}
class ThreadTestDrive {
public static void main (String[] args) {
Runnable theJob = new MyRunnable();
Thread t = new Thread(theJob);
t.start();