Java : Use TimeUnit.sleep instead of Thread.sleep

The Thread.sleep method with milliseconds is often used to cease a currently executing thread. The TimeUnit class also has the sleep method. Using the TimeUnit class makes the code a little more readable than Thread.sleep.

Note:

The Thread.sleep(Duration duration) method was added from Java 19. If you use Java 19 or later, it's also recommended to use the Thread.sleep(Duration duration) method.
This article may use translation software for your convenience. Please also check the original Japanese version.

Thread.sleep(long millis)

public static void sleep(long millis) throws InterruptedException
Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds, subject to the precision and accuracy of system timers and schedulers.

Thread.sleep ceases a thread for the specified length of milliseconds.

For example, to sleep for 5 seconds (5 seconds = 5000 milliseconds) :

final var start = System.nanoTime();

Thread.sleep(5000);

final var end = System.nanoTime();

// 5.005457 sec.
System.out.printf("%f sec.%n", (end - start) / 1000000000.0);

You can sleep the thread for about 5 seconds.

Note:

System.nanoTime is used to measure processing time. It returns a value in nanoseconds, so you convert it to seconds by dividing by 1000000000.

If you're a regular Java user, you might look at Thread.sleep(5000) and immediately know that it should stop for 5 seconds. If not, you may have forgotten the unit of sleep. In that case, you will have to check the API specification. It loses a bit of time.

TimeUnit.sleep

A TimeUnit represents time durations at a given unit of granularity and provides utility methods to convert across units, and to perform timing and delay operations in these units.

A TimeUnit is an enum class representing the unit of time. The TimeUnit has the following enum Constants.

DAYS
HOURS
MINUTES
SECONDS
MILLISECONDS
MICROSECONDS
NANOSECONDS

Although the TimeUnit is an enum, it provides some utility methods. sleep is one of them.

Now let's look at an example that uses the TimeUnit to sleep for 5 seconds.

final var start = System.nanoTime();

TimeUnit.SECONDS.sleep(5);

final var end = System.nanoTime();

// 5.004578 sec.
System.out.printf("%f sec.%n", (end - start) / 1000000000.0);

You can sleep the thread for about 5 seconds.

Thread.sleep(5000);

TimeUnit.SECONDS.sleep(5);

Compared to Thread.sleep, the amount of typing has increased somewhat. However, it becomes clear to sleep for 5 seconds.

Conclusion

Sleep time	TimeUnit	Thread
300 milliseconds	`TimeUnit.MILLISECONDS.sleep(300);`	`Thread.sleep(300);`
5 seconds	`TimeUnit.SECONDS.sleep(5);`	`Thread.sleep(5000);`
1 minute	`TimeUnit.MINUTES.sleep(1);`	`Thread.sleep(60000);`

How do you feel when you compare them side by side? Do you find TimeUnit to be easier to understand?

It may be just a little difference.

If you're the only one reading the code, you probably don't need to worry too much about code readability. However, when developing in a team, you would like to improve the readability even a little.

API Examples

Java : Use TimeUnit.sleep instead of Thread.sleep

Thread.sleep(long millis)

TimeUnit.sleep

Conclusion

Related posts