带有小数秒的Java时间戳

Question

How can I print Java Instant as a timestamp with fractional seconds like 1558766955.037 ? The precision needed is to 1/1000, as the example shows.

I tried (double) timestamp.getEpochSecond() + (double) timestamp.getNano() / 1000_000_000 , but when I convert it to string and print it, it shows 1.558766955037E9 .

Answer 1

The result you're seeing is the secientific (e-) notation of the result you wanted to get. In other words, you have the right result, you just need to properly format it when you print it:

Instant timestamp = Instant.now();
double d = (double) timestamp.getEpochSecond() + (double) timestamp.getNano() / 1000_000_000;
System.out.printf("%.2f", d);

Answer 2

As others pointed out it is formatting issue. For your specific format you could use Formatter with Locale that supports dot delimetted fractions :

Instant now = Instant.now();

double val = (double) now.getEpochSecond() + (double) now.getNano() / 1000_000_000;

String value = new Formatter(Locale.US)
                .format("%.3f", val)
                .toString();

System.out.print(value);

Prints :

1558768149.514

Answer 3

System.out.printf("%.3f", instant.toEpochMilli() / 1000.0)应该可以正常工作。