4- Pausing a Thread

Jul 03, 2026 14:39 · 2:35 · English · Whisper Turbo · 2 Høgtalar

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Forelesningsindeks

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The third class in Java has a sleep method which we can use for pausing the execution

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of a thread.

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With this we can simulate a long -running operation,

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like downloading a file that takes a few seconds.

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So in our task class,

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after printing this message,

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let's call thread dot sleep.

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Here we can pass the delay in milliseconds,

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let's say 5000.

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So this will suspend the current thread for roughly 5000 milliseconds or

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five seconds.

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It's not going to be exactly five seconds because this is dependent on the underlying

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operating system.

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But we can assume that this thread will be sleeping for roughly five seconds and

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during this time other threads can get processor time.

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Now, the Java compiler is complaining that we have an unhandled exception here.

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That is interrupted exception.

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This is an exception that gets thrown if you try to interrupt the thread that is

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sleeping. We'll talk about interrupting a thread later.

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But for now,

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let's handle this exception.

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So we put the caret on this sleep method,

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press alt and enter and wrap this inside a try

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catch block.

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Pretty easy.

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Now,

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after five seconds of delay,

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let's print another message like download complete.

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We can also add the thread name for clarity,

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so plus thread .currentThread .getName.

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Now,

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back to our demo class,

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here we are starting 10 threads for downloading 10 files.

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When I run this program,

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you will see that these 10 threads will start at the same time,

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and after 5 seconds,

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they all complete.

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Take a look.

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So,

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run,

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they all started,

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now 1,

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and 5,

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they all complete.

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Now if you had a single threaded application,

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downloading these 10 files would take 50 seconds instead of 5 seconds,

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because each download would start once another download finished.

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So multi -threading makes our applications faster and more responsive.

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Now,

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what if we try to download,

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let's say,

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100 or 1000 files concurrently?

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My machine has 4 cores and 8 threads available.

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So how is that going to work?

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Well,

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the Java virtual machine has what we call a thread scheduler.

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The job of this scheduler is to decide what threads to run for how long.

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So if you have more tasks than the available threads,

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the scheduler switches between these tasks,

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giving each a slice of the CPU time.

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This happens so fast that gives us the illusion that these tasks are being

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executed in parallel,

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but that's parallelism at software level.

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