Calculate the age using the date of birth

Question

I am developing an android app to find the age from the date of birth provided by user.. three edit-texts are there one for day and other two for month and year. I got the c

Answer 1

tl;dr

Period.between( 
    LocalDate.of( Integer.parseInt( … ) , … , … ) ,  // ( year, month, dayOfMonth )
    LocalDate.now( ZoneId.of( "Pacific/Auckland" ) ) 
).getYears()

Details

You are using troublesome old date-time classes, now legacy, supplanted by the java.time classes.

The LocalDate class represents a date-only value without time-of-day and without time zone.

Unlike the legacy classes, the months have sane numbering, 1-12 for January-December.

LocalDate localDate = LocalDate.of( Integer.parseInt( … ) , … , … ) ;  // year , month , day

A time zone is crucial in determining a date. For any given moment, the date varies around the globe by zone. For example, a few minutes after midnight in Paris France is a new day while still “yesterday” in Montréal Québec.

Specify a proper time zone name in the format of continent/region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 3-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!).

ZoneId z = ZoneId.of( "America/Montreal" );
LocalDate today = LocalDate.now( z );

Representing a span of time in granularity of days-months-years is done with the Period class.

Period age = Period.between( localDate , today );

To get a String in standard ISO 8601 format, call age.toString(). Or interrogate for each part, years, months, days.

int y = age.getYears();
int m = age.getMonths();
int d = age.getDays();

---

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

Where to obtain the java.time classes?

• Java SE 8, Java SE 9, and later
  • Built-in.
  • Part of the standard Java API with a bundled implementation.
  • Java 9 adds some minor features and fixes.
• Java SE 6 and Java SE 7
  • Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
• Android
  • The ThreeTenABP project adapts ThreeTen-Backport (mentioned above) for Android specifically.
  • See How to use ThreeTenABP….

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.