How do I measure time elapsed in Java?

To measure time elapsed in Java, you can use the System.currentTimeMillis() method to get the current time in milliseconds, then subtract the start time from the end time to get the elapsed time. Here's an example of how you can measure time elapsed in Java:

long startTime = System.currentTimeMillis();
// code to be measured goes here
long endTime = System.currentTimeMillis();
long elapsedTime = endTime - startTime;
System.out.println("Elapsed time in milliseconds: " + elapsedTime);

You can also use the System.nanoTime() method to get the current time in nanoseconds, if you need more precision.

Alternatively, you can use the java.time.Instant class to measure time elapsed. Here's an example of how you can measure time elapsed using Instant:

Instant start = Instant.now();
// code to be measured goes here
Instant end = Instant.now();
Duration elapsed = Duration.between(start, end);
System.out.println("Elapsed time: " + elapsed.toMillis() + " milliseconds");

The Duration class represents a duration of time, in seconds and nanoseconds. You can use the toMillis() method to convert the elapsed time to milliseconds.