{"id":22542,"date":"2014-03-10T19:00:20","date_gmt":"2014-03-10T17:00:20","guid":{"rendered":"http:\/\/www.javacodegeeks.com\/?p=22542"},"modified":"2014-03-10T08:58:41","modified_gmt":"2014-03-10T06:58:41","slug":"whats-new-in-java-8-date-api","status":"publish","type":"post","link":"https:\/\/www.javacodegeeks.com\/2014\/03\/whats-new-in-java-8-date-api.html","title":{"rendered":"What’s new in Java 8 – Date API"},"content":{"rendered":"

With the final release of Java 8 around the corner, one of the new features I\u2019m excited about is the new Date<\/a> API, a result of the work on JSR 310<\/a>. While Lambda expressions are certainly the big draw of Java 8, having a better way to work with dates is a decidedly welcome addition. This is a quick post (part 1 of 2 or 3) showing some highlights of the new Date functionality, this time mostly around the LocalDate<\/a> class.<\/p>\n

Creating New Date Objects<\/h2>\n

Creating a new Date object representing a specific day is as easy as:
\n <\/p>\n

LocalDate today = LocalDate.parse(\"2014-02-27\");\r\n\/\/or this method\r\nLocalDate bday = LocalDate.of(2014,3,18);<\/pre>\n
Adding To Dates<\/h2>\n
As an example of the ease with which we can work with dates in Java 8, consider the case where we need to add either days, months or years to an existing date. There are the methods LocalDate.plusDays<\/code>,LocalDate.plusWeeks<\/code>, LocalDate.plusMonths<\/code> LocalDate.plusYears<\/code>. There is also a generic LocalDate.plus<\/code> method where you specify how much to add and the time unit via a TemporalUnit<\/a> type. Here some examples:<\/p>\n
@Test\r\n\tpublic void test_add_to_date() {\r\n\t \r\n\t    LocalDate oneMonthFromNow = today.plusDays(30);\r\n\t    assertTrue(oneMonthFromNow.isEqual(LocalDate.parse(\"2014-03-29\")));\r\n\t \r\n\t    LocalDate nextMonth = today.plusMonths(1);\r\n\t    assertTrue(nextMonth.isEqual(LocalDate.parse(\"2014-03-27\")));\r\n\t \r\n\t    LocalDate future = today.plus(4, ChronoUnit.WEEKS);\r\n\t    assertTrue(future.isEqual(LocalDate.parse(\"2014-03-27\")));\r\n\t \r\n\t}<\/pre>\n
Subtracting From Dates<\/h2>\n
To subtract days, weeks, months or years from a date there the expected methods: LocalDate.minusDays<\/code>, LocalDate.minusMonths<\/code> etc. Here\u2019s some examples of subtracting from a date:
 
<\/div> <\/div><\/p>\n
@Test\r\n    public void test_subtract_from_date() {\r\n\r\n        assertThat(today.minusWeeks(1).toString(), is(\"2014-02-20\"));\r\n\r\n        assertThat(today.minusMonths(2).toString(), is(\"2013-12-27\"));\r\n\r\n        assertThat(today.minusYears(4).toString(), is(\"2010-02-27\"));\r\n\r\n        Period twoMonths = Period.ofMonths(2);\r\n\r\n        assertThat(today.minus(twoMonths).toString(), is(\"2013-12-27\"));\r\n\r\n    }<\/pre>\n
In this example we also introduced the Period<\/a> object.<\/p>\n
Determining Difference Between Dates<\/h2>\n
It could be argued getting the difference between two dates was the most painful operation to do with dates prior to Java 8. The new Date API makes determining the amount of days,weeks,months or years between dates equally as easy with the LocalDate.until<\/code> method:<\/p>\n
@Test\r\n    public void test_get_days_between_dates() {\r\n        LocalDate vacationStart = LocalDate.parse(\"2014-07-04\");\r\n        Period timeUntilVacation = today.until(vacationStart);\r\n\r\n        assertThat(timeUntilVacation.getMonths(), is(4));\r\n\r\n        assertThat(timeUntilVacation.getDays(), is(7));\r\n\r\n        assertThat(today.until(vacationStart, ChronoUnit.DAYS), is(127L));\r\n\r\n        LocalDate libraryBookDue = LocalDate.parse(\"2000-03-18\");\r\n\r\n        assertThat(today.until(libraryBookDue).isNegative(), is(true));\r\n\r\n        assertThat(today.until(libraryBookDue, ChronoUnit.DAYS), is(-5094L));\r\n\r\n        LocalDate christmas = LocalDate.parse(\"2014-12-25\");\r\n        assertThat(today.until(christmas, ChronoUnit.DAYS), is(301L));\r\n\r\n    }<\/pre>\n
In this example we see the use of the Period<\/code> object again.<\/p>\n
Conclusion<\/h2>\n
We\u2019ve wrapped up our quick tour of the LocalDate<\/code> and the Java 8 Date API. Obviously, there is so much more to discover about working with dates and time in Java 8, this post is just a quick introduction. Thanks for your time.<\/p>\n
Resources<\/h2>\n