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Subsections
- Explain what threads are, how they work, and when to use them.
- Create threads using the Thread class.
- Create threads using the Runnable interface.
- Describe thread states.
- Understand the methods that are used when manipulating threads.
- Many applications work without multiple threads of concurrency.
- In this world, a sequence of actions is completed in a linear, one-thread-of-thought-at-a-time manner.
- Java makes it easy for developers to create multiple threads that essentially run simultaneously. (How this really works depends on what operating system your application is running on.)
- A thread is considered lightweight because it runs within the context of a full-blown program.
- new - an empty thread, with no system resources allocated; all you can do is start it.
- runnable - the start() method is called, and the thread is not dead or in the ``not runnable'' state.
- not runnable - sleep() is invoked, thread calls wait(), thread is blocking on I/O.
- dead - the end of the run() method has been reached.
- Extend the java.lang.Thread class and override its run() method.
- The run() method defines the behavior of the thread while it is running.
- When the run() method ends, the thread goes into the dead state.
- As a developer, you call the start() method of the thread; the JVM calls the run() method.
- Never call the run() method directly.
- Cannot always extend the Thread class because of single inheritance.
- Implement the java.lang.Runnable interface (must implement the run() method).
- Include a Thread attribute in the class.
- The run() method still defines the behavior of the thread while it is running.
- sleep(long ms) - causes the thread to sleep for the specified number of milliseconds.
- yield() - provides a hint to the scheduler that this doesn't have to run at the current time, so the scheduler can choose another thread to run if need be.
- join() - used to let one thread wait for another to terminate.
- interrupt() - used to request that the thread cancel itself.
- notifyAll() - wakes up all waiting threads.
- wait() - used to pause the thread, presumably while it waits for some condition to be satisfied.
- The Java Programming Language - excellent chapter on threads.
- Sun's Java Tutorial, at http://java.sun.com/docs/books/tutorial/, or more specifically http://java.sun.com/docs/books/tutorial/essential/threads/index.html.
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