42 lines
1.9 KiB
Markdown
42 lines
1.9 KiB
Markdown
1:
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the output is Calling run()
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Running in: main
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Calling start()
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Running in: Thread-2
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t1.run() does not start a new thread.
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It just calls the run() method like a normal method call, and it executes on the current thread.
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t2.start() creates a new thread and then that new thread executes run(), so current Thread Name becomes Thread-2.
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run() is just a normal method call, so it runs in the current thread.
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start() creates a new thread, and that new thread executes run().
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2:
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Output:
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Main thread ends.
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It may also print:
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Daemon thread running…
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a few times, or sometimes not at all.
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Why:
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Because the created thread is a daemon thread. Daemon threads run in the background, and when the main thread finishes, the JVM can stop immediately.
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So the daemon thread may not complete its loop.
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If thread.setDaemon(true) is removed:
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Then the thread becomes a user thread (non-daemon thread).
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and the JVM will wait for it to finish, so "Daemon thread running..." will print many times until the loops end.
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Real-life uses of daemon threads:
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Garbage collection
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Background auto-save
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Cache cleanup
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Monitoring or logging services
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Timer or scheduler tasks running in background
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3:
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What output do you get from the program?
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Thread is running using a …!
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What is the () -> { ... } syntax called?
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This is called a lambda expression.
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How is this code different from creating a class that extends Thread or implements Runnable?
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This is a shorter and cleaner way to write thread code.
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Instead of creating a separate class, the task is written directly inside the lambda expression.
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