Timestamp can't be parsed Issue java.time.format.DateTimeParseException: Text '9/25/2020, 12:46:00 PM' could not be parsed at index 0

Question

I am attempting to capture the time before and after I check a timestamp value on a webpage and then confirm my timestamp falls in between those times. However, I'm struggling to convert my String timestamp into a comparable format in a clean way.

        Instant b4 = Instant.now();
                    
        //My code submites a file that then triggers the timestamp. I retrieve it as a string
        //exa string"9/25/2020, 11:03:18 AM"

        DateTimeFormatter dtf = DateTimeFormatter
                .ofPattern("MM/dd/yyyy, HH:mm:ss a")
                .withZone(ZoneId.systemDefault());
        Instant instantTimestamp = Instant.from(dtf.parse(timeStamp));

        Instant after = Instant.now();          

        if (instantTimestamp.isAfter(b4) && instantTimestamp.isBefore(after)) {
            testPass = true;
        }

        Assert.assertTrue(testPass);

My Error: java.time.format.DateTimeParseException: Text '9/25/2020, 12:46:00 PM' could not be parsed at index 0

Answer 1

There is a mismatch in the format for the month and its value in the string. The format is MM which specifies two digits but the value is 9 which is a single digit. You can use single letters for month, day, year, hour, minute, seconds etc. to accommodate all allowable numbers of digits. Also, I suggest you parse it in a case-insensitive way so that upper and lower case (e.g. AM and am) both can be accommodated.

import java.time.Instant;
import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        // Given date-time string
        String dateTimeString = "9/25/2020, 12:46:00 PM";

        DateTimeFormatter dtf = new DateTimeFormatterBuilder()
                                .parseCaseInsensitive()
                                .appendPattern("M/d/u, h:m:s a")
                                .toFormatter(Locale.ENGLISH);

        // Convert the given date-time string to LocalDateTime
        LocalDateTime ldt = LocalDateTime.parse(dateTimeString, dtf);
        System.out.println(ldt);

        // Convert to LocalDateTime Instant if required
        Instant instant = ldt.toInstant(ZoneOffset.UTC);
        System.out.println(instant);
    }
}

Output:

2020-09-25T12:46
2020-09-25T12:46:00Z

ONLINE DEMO

If the timezone to which this Date-Time belongs is different from UTC, convert it to Instant through ZonedDateTime e.g.

Instant instant = ldt.atZone(ZoneId.of("America/Los_Angeles")).toInstant();

Learn more about the modern Date-Time API from Trail: Date Time.