We have consistent ZonedDateTime type in application, so we do not
prefer to change that.
Why do you think 2011-01-19T04:00Z[UTC] is inconsistent? A date-time object is supposed to hold (and provide methods/functions to operate with) only the date, time, and time-zone information. It is not supposed to store any formatting information; otherwise, it will violate the Single-responsibility principle. The formatting should be handled by a formating class e.g. DateTimeFormatter (for modern date-time API), DateFormat (for legacy java.util date-time API) etc.
Every class is supposed to override the toString() function; otherwise, Object#toString will be returned when its object will be printed. A ZonedDateTime has date, time and time-zone information. Given below is how its toString() for time-part has been implemented:
@Override
public String toString() {
StringBuilder buf = new StringBuilder(18);
int hourValue = hour;
int minuteValue = minute;
int secondValue = second;
int nanoValue = nano;
buf.append(hourValue < 10 ? "0" : "").append(hourValue)
.append(minuteValue < 10 ? ":0" : ":").append(minuteValue);
if (secondValue > 0 || nanoValue > 0) {
buf.append(secondValue < 10 ? ":0" : ":").append(secondValue);
if (nanoValue > 0) {
buf.append('.');
if (nanoValue % 1000_000 == 0) {
buf.append(Integer.toString((nanoValue / 1000_000) + 1000).substring(1));
} else if (nanoValue % 1000 == 0) {
buf.append(Integer.toString((nanoValue / 1000) + 1000_000).substring(1));
} else {
buf.append(Integer.toString((nanoValue) + 1000_000_000).substring(1));
}
}
}
return buf.toString();
}
As you can see, the second and nano parts are included in the returned string only when they are greater than 0. It means that you need to use a formatting class if you want these (second and nano) zeros in the output string. Given below is an example:
import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
String input = "1/19/2011 4:00:00.000000 AM";
// Formatter for input string
DateTimeFormatter inputFormatter = new DateTimeFormatterBuilder()
.parseCaseInsensitive()
.appendPattern("M/d/u H:m:s.n a")
.toFormatter(Locale.ENGLISH);
ZonedDateTime zdt = LocalDateTime.parse(input, inputFormatter).atZone(ZoneOffset.UTC);
// Print `zdt` in default format i.e. the string returned by `zdt.toString()`
System.out.println(zdt);
// Formatter for input string
DateTimeFormatter outputFormatter = DateTimeFormatter.ofPattern("uuuu-MM-dd'T'HH:mm:ss.nnnnnnz");
String output = zdt.format(outputFormatter);
System.out.println(output);
}
}
Output:
2011-01-19T04:00Z
2011-01-19T04:00:00.000000Z
Food for thought:
public class Main {
public static void main(String[] args) {
double d = 5.0000;
System.out.println(d);
}
}
What output do you expect from the code given above? Does 5.0 represent a value different from 5.0000? How will you print 5.0000? [Hint: Check String#format, NumberFormat, BigDecimal etc.]
