Using ZoneDateTime.parse how would you parse the following

Question

using ZoneDateTime.parse, how would you parse the following

Mon Jul 01 2019 00:00:00 GMT-0500 (Central Daylight Time)

Have to use zoneDateTime.parse is a must.

This is not for homework but for work and standards are already set.

Answer 1

To solve a problem like this, first try to build a formatter that will produce the same output. Then use that for parsing.

Read the javadoc of DateTimeFormatter to learn what formatting symbols can produce the desired output.

Mon                      E      day-of-week         text         Tue; Tuesday; T
Jul                      M/L    month-of-year       number/text  7; 07; Jul; July; J
01                       d      day-of-month        number       10
2019                     u      year                year         2004; 04
00                       H      hour-of-day (0-23)  number       0
:                        :      fixed text
00                       m      minute-of-hour      number       30
:                        :      fixed text
00                       s      second-of-minute    number       55
GMT                      'GMT'  fixed text
-0500                    x      zone-offset         offset-x     +0000; -08; -0830; -08:30; -083015; -08:30:15;
(                        (      fixed text
Central Daylight Time    z      time-zone name      zone-name    Pacific Standard Time; PST
)                        )      fixed text

Then read the fine print to learn how many of each format letter you need, eg that you need dd to get 2-digit day-of-month with leading zero.

Testing the result:

String expected = "Mon Jul 01 2019 00:00:00 GMT-0500 (Central Daylight Time)";
String format = "EEE MMM dd uuuu HH:mm:ss 'GMT'xx (zzzz)";

ZonedDateTime zdt = ZonedDateTime.of(2019, 7, 1, 0, 0, 0, 0, ZoneId.of("America/Chicago"));
System.out.println(zdt.format(DateTimeFormatter.ofPattern(format)));
System.out.println(expected);

Output

Mon Jul 01 2019 00:00:00 GMT-0500 (Central Daylight Time)
Mon Jul 01 2019 00:00:00 GMT-0500 (Central Daylight Time)

Use it

String input = "Mon Jul 01 2019 00:00:00 GMT-0500 (Central Daylight Time)";
String format = "EEE MMM dd uuuu HH:mm:ss 'GMT'xx (zzzz)";

ZonedDateTime zdt = ZonedDateTime.parse(input, DateTimeFormatter.ofPattern(format));
System.out.println(zdt);

Output

2019-07-01T00:00-05:00[America/Chicago]