How to convert "hh mm a" format string to seconds in java

Question

I have string "6:00 AM" i want to convert this string to seconds or milliseconds in java. Please suggest me standard way to convert this.

seconds from midnight "00:00 am"

Assuming you have Java 8, I would use the `LocalTime` class, which has a `parse` method and a `toSecondOfDay` method. If you have Java 7 or below, you might want to get your hands on the Joda library. — Dawood ibn Kareem, Jan 15 '15 at 05:21
possible duplicate of [How can I find the amount of seconds passed from the midnight with Java?](http://stackoverflow.com/questions/4389500/how-can-i-find-the-amount-of-seconds-passed-from-the-midnight-with-java) — Basil Bourque, Jan 16 '15 at 10:26
@SameerKazi My guess is that the down vote is due to you posting a duplicate question instead of bothering to read the hundreds of existing Questions and Answers on this topic. — Basil Bourque, Jan 16 '15 at 10:28
@SameerKazi Yes, you can delete your own question. But don't do so in this case. The answer by MadProgrammer is too good to lose. In only wish he or she had placed that answer on one of the original Questions rather than a duplicate. — Basil Bourque, Jan 16 '15 at 17:04

score 11 · Accepted Answer · edited Jun 20 '20 at 09:12

Java 7

Convert the String to a Date...

SimpleDateFormat sdf = new SimpleDateFormat("hh:mm a");
TimeZone gmt = TimeZone.getTimeZone("GMT");
sdf.setTimeZone(gmt);
Date date = sdf.parse("6:00 am");

Because there is no date information, this will be the milliseconds since the epoch + your time.

Convert the Date to seconds

long seconds = date.getTime() / 1000;
System.out.println(seconds);

Which outputs 21600 seconds, 360 minutes or 6 hours

Java 8

Something more like...

LocalTime lt = LocalTime.parse("6:00 AM", 
                DateTimeFormatter.ofPattern("h:m a"));
System.out.println(lt.toSecondOfDay());

...for example...

JodaTime

LocalTime lt = LocalTime.parse("6:00 am", 
                new DateTimeFormatterBuilder().
                                appendHourOfDay(1).
                                appendLiteral(":").
                                appendMinuteOfHour(1).
                                appendLiteral(" ").
                                appendHalfdayOfDayText().toFormatter());
LocalTime midnight = LocalTime.MIDNIGHT;
Duration duration = new Duration(midnight.toDateTimeToday(), lt.toDateTimeToday());
System.out.println(duration.toStandardSeconds().getSeconds());

Great answer! **To future visitors:** The `java.util` Date-Time API and their formatting API, `SimpleDateFormat` are outdated and error-prone. It is recommended to stop using them completely and switch to the [modern Date-Time API](https://www.oracle.com/technical-resources/articles/java/jf14-Date-Time.html). Also, quoted below is a notice from the [home page of **Joda-Time**](https://www.joda.org/joda-time/): *Note that from Java SE 8 onwards, users are asked to migrate to `java.time` (JSR-310) - a core part of the JDK which replaces this project.* — Arvind Kumar Avinash, Dec 30 '22 at 13:07

Dongqing · Answer 2 · 2015-01-15T07:33:27.703

1

Joda-time is a good choice when you need to deal with date time calculation.

import org.joda.time.*;
import org.joda.time.format.*;

DateTimeFormatter fmt = DateTimeFormat.forPattern("K:mm a");
DateTime end = fmt.parseDateTime("6:00 AM");
DateTime start = fmt.parseDateTime("00:00 AM");
Interval interval = new Interval(start,end);
long millSec = interval.toDurationMillis();
long second = interval.toDuration().getStandardSeconds();

edited Jan 15 '15 at 07:33

answered Jan 15 '15 at 05:44

Dongqing

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What version of Joda-Time are you using? I tried using 2.4 and 2.7 but both give me an error for `Interval interval = new Interval(start,end);` – MadProgrammer Jan 15 '15 at 05:53

How to convert "hh mm a" format string to seconds in java

2 Answers2

Java 7

Java 8

JodaTime