— Scott McNealy, Sun Microsystems Chairman, President and ceo

1
Make one instance of RyanAndMonicaJob. 
The RyanAndMonicaJob class is the Runnable (the job to do), 
and since both Monica and Ryan do the same thing (check 
balance and withdraw money), we need only one instance.
BankAccount
int balance
getBalance()
withdraw()
RyanAndMonicaJob
BankAccount account
run()
makeWithdrawal()
Runnable
2
Make two threads with the same Runnable 
(the RyanAndMonicaJob instance)
RyanAndMonicaJob theJob = new RyanAndMonicaJob();
Thread one = new Thread(theJob);
Thread two = new Thread(theJob);
3
Name and start the threads 
one.setName(“Ryan”);
two.setName(“Monica”);
one.start();
two.start();
4
Watch both threads execute the run() method
(check the balance and make a withdrawal)
One thread represents Ryan, the other represents Monica. 
Both threads continually check the balance and then make a 
withdrawal, but only if it’s safe! 
In the run() method, do 
exactly what Ryan and 
Monica would do—check 
the balance and, if 
there’s enough money, 
make the withdrawal.
This should protect 
against overdrawing the 
account.
Except... Ryan and 
Monica always fall 
asleep after they 
check the balance but 
before they fi nish the 
withdrawal. 
if (account.getBalance() >= amount) {
try {
Thread.sleep(500);
} catch(InterruptedException ex) {ex.printStackTrace(); }
}
Ryan and Monica 
code

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networking 
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4