I am new to Java. I have a requirement to calculate the number of days, hour, time, sec from a given date to today, current time.

For example, I am getting 2 fields from database: Date and Time.
Date field is in the format Wednesday 02-October-2022 and Time field in the format 11:51:1 PM

In my Java class, I am able to pass these 2 field in String format:

public String getLastRun(String failedDate, String failedTime)
{

}

String failedDate, String failedTime are the Date and Time I got from DB in above format.

Now the issue is I need to calculate the number of days, hour, time, sec passed from that Date and time taken as input.

So, if current date is Thursday 02-November-2022 and time is 11:51:1 PM, I can calculate the number of days, hour, time, sec passed.
Example: Output: Last service failed 30 Days 12 hours 55 minutes 45 seconds Kind of output calculating the given Date and time field as input to this current Date and time?

So far, I have taken this Date and Time as input in this format of Wednesday 02-October-2022 and 11:51:1 PM in the Java class, but I am still not sure about:

1. How to generate or fetch current Date and Time in this format in Java code?
2. How to calculate the number of days, hour, time, sec passed from the given format with current Date and Time?

I have checked these following links: Link1, Link2 with local dates, but none of these have helped me to get the number of days, hour, time, sec from the given date and time format dynamically.
I even tried with SimpleDateFormat as mentioned here but not able to get with this format.

Any sample or pointer to start with will be helpful.
Pls Note: Time zone is IST Asia/Kolkata

CodePudding user response：

Parse your date as a LocalDate using DateTimeFormatter. This has been covered many times already on Stack Overflow.

Parse your time of day as a LocalTime using DateTimeFormatter. This has been covered many times already on Stack Overflow.

Specify your intended time zone.

ZoneId zone = ZoneId.of( "Asia/Kolkata" ) ;

Combine.

ZonedDateTime zdt = ZonedDateTime.of( date , time , zone ) ;

Adjust to UTC by extracting an Instant.

Instant then = zdt.toInstant () ;

Use Duration to calculate elapsed time on a scale of 24-hour long “days” (not calendar days), hours, minutes, seconds, and nanos.

Duration duration = Duration.between ( then , Instant.now() ) ;

The ideal solution would be educating the publisher of your data on using standard ISO 8601 formats.

CodePudding user response：

Your steps should be as follows:

1. Parse the date string into LocalDate using the applicable DateTimeFormatter.
2. Parse the time string into LocalTime using the applicable DateTimeFormatter.
3. Create an instance of LocalDateTime using the instances of LocalDate and LocalTime obtained from the above steps.
4. Find the Duration between the obtained LocalDateTime and the current date-time.
5. Get the days, hours, minutes, seconds from the obtained Duration.

Demo:

import java.time.Duration;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;

public class Main {
  public static void main(String[] args) {
    // Test
    System.out.println(getLastRun("Wednesday 05-October-2022", "11:51:1 PM"));
  }

  public static String getLastRun(String failedDate, String failedTime) {
    LocalDateTime givenDateTime = LocalDateTime.of(
        LocalDate.parse(failedDate, DateTimeFormatter.ofPattern("EEEE dd-MMMM-uuuu", Locale.ENGLISH)),
        LocalTime.parse(failedTime, DateTimeFormatter.ofPattern("h:m:s a", Locale.ENGLISH)));

    LocalDateTime now = LocalDateTime.now();

    Duration duration = givenDateTime.isAfter(now) ? Duration.between(now, givenDateTime)
        : Duration.between(givenDateTime, now);

    return String.format("Last service failed %d Days %d hours %d minutes %d seconds",
        duration.toDaysPart(), duration.toHoursPart(), duration.toMinutesPart(), duration.toSecondsPart());
  }
}

Output:

Last service failed 27 Days 21 hours 27 minutes 49 seconds

Learn more about the modern Date-Time API from Trail: Date Time and about the Duration through Q/As tagged with duration.