System.out.println(name + " got: " +
Shared.ai.getAndSet(i));
}
}
In the program, a static AtomicInteger named ai is created by Shared. Then, three threads
of type AtomThread are created. Inside run( ), Shared.ai is modified by calling getAndSet( ).
This method returns the previous value and then sets the value to the one passed as an
argument. The use of AtomicInteger prevents two threads from writing to ai at the same time.
In general, the atomic operations offer a convenient (and possibly more efficient) alternative
to the other synchronization mechanisms when only a single variable is involved.
The Concurrency Utilities Versus Java's Traditional Approach
Given the power and flexibility found in the new concurrency utilities, it is natural to ask
the following question: Do they replace Java's traditional approach to multithreading and
synchronization? The answer is a resounding no! The original support for multithreading
and the built-in synchronization features are still the mechanism that should be employed
for many, many Java programs, applets, and servlets. For example, synchronized, wait( ),
and notify( ) offer elegant solutions to a wide range of problems. However, when extra
control is needed, the concurrency utilities are now available to handle the chore.
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