如何用Java计算某人的年龄？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/1116123/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How do I calculate someone's age in Java?
提问by nojevive
I want to return an age in years as an int in a Java method. What I have now is the following where getBirthDate() returns a Date object (with the birth date ;-)):
我想在 Java 方法中将年龄作为 int 返回。我现在拥有的是以下内容，其中 getBirthDate() 返回一个 Date 对象（带有出生日期；-)）：
public int getAge() {
long ageInMillis = new Date().getTime() - getBirthDate().getTime();
Date age = new Date(ageInMillis);
return age.getYear();
}
But since getYear() is deprecated I'm wondering if there is a better way to do this? I'm not even sure this works correctly, since I have no unit tests in place (yet).
但是由于 getYear() 已被弃用，我想知道是否有更好的方法来做到这一点？我什至不确定这是否正常工作，因为我还没有进行单元测试（还没有）。
采纳答案by duffymo
JDK 8 makes this easy and elegant:
JDK 8 使这变得简单而优雅：
public class AgeCalculator {
public static int calculateAge(LocalDate birthDate, LocalDate currentDate) {
if ((birthDate != null) && (currentDate != null)) {
return Period.between(birthDate, currentDate).getYears();
} else {
return 0;
}
}
}
A JUnit test to demonstrate its use:
用于演示其使用的 JUnit 测试：
public class AgeCalculatorTest {
@Test
public void testCalculateAge_Success() {
// setup
LocalDate birthDate = LocalDate.of(1961, 5, 17);
// exercise
int actual = AgeCalculator.calculateAge(birthDate, LocalDate.of(2016, 7, 12));
// assert
Assert.assertEquals(55, actual);
}
}
Everyone should be using JDK 8 by now. All earlier versions have passed the end of their support lives.
现在每个人都应该使用 JDK 8。所有早期版本的支持生命周期都已结束。
回答by cletus
Calendar now = Calendar.getInstance();
Calendar dob = Calendar.getInstance();
dob.setTime(...);
if (dob.after(now)) {
throw new IllegalArgumentException("Can't be born in the future");
}
int year1 = now.get(Calendar.YEAR);
int year2 = dob.get(Calendar.YEAR);
int age = year1 - year2;
int month1 = now.get(Calendar.MONTH);
int month2 = dob.get(Calendar.MONTH);
if (month2 > month1) {
age--;
} else if (month1 == month2) {
int day1 = now.get(Calendar.DAY_OF_MONTH);
int day2 = dob.get(Calendar.DAY_OF_MONTH);
if (day2 > day1) {
age--;
}
}
// age is now correct
回答by Brian Agnew
Check out Joda, which simplifies date/time calculations (Joda is also the basis of the new standard Java date/time apis, so you'll be learning a soon-to-be-standard API).
查看Joda，它简化了日期/时间计算（Joda 也是新标准 Java 日期/时间 API 的基础，因此您将学习一个即将成为标准的 API）。
EDIT: Java 8 has something very similarand is worth checking out.
编辑：Java 8 有一些非常相似的东西，值得一试。
e.g.
例如
LocalDate birthdate = new LocalDate (1970, 1, 20);
LocalDate now = new LocalDate();
Years age = Years.yearsBetween(birthdate, now);
which is as simple as you could want. The pre-Java 8 stuff is (as you've identified) somewhat unintuitive.
这就像您想要的那样简单。Java 8 之前的东西（如您所见）有些不直观。
回答by John O
回答by Craigo
If you are using GWT you will be limited to using java.util.Date, here is a method that takes the date as integers, but still uses java.util.Date:
如果您使用 GWT，您将仅限于使用 java.util.Date，这里有一个将日期作为整数但仍使用 java.util.Date 的方法：
public int getAge(int year, int month, int day) {
Date now = new Date();
int nowMonth = now.getMonth()+1;
int nowYear = now.getYear()+1900;
int result = nowYear - year;
if (month > nowMonth) {
result--;
}
else if (month == nowMonth) {
int nowDay = now.getDate();
if (day > nowDay) {
result--;
}
}
return result;
}
回答by John B
The fields birth and effect are both date fields:
字段birth 和effect 都是日期字段：
Calendar bir = Calendar.getInstance();
bir.setTime(birth);
int birthNm = bir.get(Calendar.DAY_OF_YEAR);
int birthYear = bir.get(Calendar.YEAR);
Calendar eff = Calendar.getInstance();
eff.setTime(effect);
This basically a modification of John O's solution without using depreciated methods. I spent a fair amount of time trying to get his code to work in in my code. Maybe this will save others that time.
这基本上是对 John O 解决方案的修改，而不使用折旧方法。我花了相当多的时间试图让他的代码在我的代码中工作。也许这会节省其他人的时间。
回答by cass
This is an improved version of the one above... considering that you want age to be an 'int'. because sometimes you don't want to fill your program with a bunch of libraries.
这是上述版本的改进版本......考虑到您希望年龄为“int”。因为有时你不想用一堆库来填充你的程序。
public int getAge(Date dateOfBirth) {
int age = 0;
Calendar born = Calendar.getInstance();
Calendar now = Calendar.getInstance();
if(dateOfBirth!= null) {
now.setTime(new Date());
born.setTime(dateOfBirth);
if(born.after(now)) {
throw new IllegalArgumentException("Can't be born in the future");
}
age = now.get(Calendar.YEAR) - born.get(Calendar.YEAR);
if(now.get(Calendar.DAY_OF_YEAR) < born.get(Calendar.DAY_OF_YEAR)) {
age-=1;
}
}
return age;
}
回答by Stradivariuz
public int getAge(Date dateOfBirth)
{
Calendar now = Calendar.getInstance();
Calendar dob = Calendar.getInstance();
dob.setTime(dateOfBirth);
if (dob.after(now))
{
throw new IllegalArgumentException("Can't be born in the future");
}
int age = now.get(Calendar.YEAR) - dob.get(Calendar.YEAR);
if (now.get(Calendar.DAY_OF_YEAR) < dob.get(Calendar.DAY_OF_YEAR))
{
age--;
}
return age;
}
回答by Farhan Munir
/**
* This Method is unit tested properly for very different cases ,
* taking care of Leap Year days difference in a year,
* and date cases month and Year boundary cases (12/31/1980, 01/01/1980 etc)
**/
public static int getAge(Date dateOfBirth) {
Calendar today = Calendar.getInstance();
Calendar birthDate = Calendar.getInstance();
int age = 0;
birthDate.setTime(dateOfBirth);
if (birthDate.after(today)) {
throw new IllegalArgumentException("Can't be born in the future");
}
age = today.get(Calendar.YEAR) - birthDate.get(Calendar.YEAR);
// If birth date is greater than todays date (after 2 days adjustment of leap year) then decrement age one year
if ( (birthDate.get(Calendar.DAY_OF_YEAR) - today.get(Calendar.DAY_OF_YEAR) > 3) ||
(birthDate.get(Calendar.MONTH) > today.get(Calendar.MONTH ))){
age--;
// If birth date and todays date are of same month and birth day of month is greater than todays day of month then decrement age
}else if ((birthDate.get(Calendar.MONTH) == today.get(Calendar.MONTH )) &&
(birthDate.get(Calendar.DAY_OF_MONTH) > today.get(Calendar.DAY_OF_MONTH ))){
age--;
}
return age;
}
回答by Kevin
Try to copy this one in your code, then use the method to get the age.
尝试在您的代码中复制这个，然后使用该方法获取年龄。
public static int getAge(Date birthday)
{
GregorianCalendar today = new GregorianCalendar();
GregorianCalendar bday = new GregorianCalendar();
GregorianCalendar bdayThisYear = new GregorianCalendar();
bday.setTime(birthday);
bdayThisYear.setTime(birthday);
bdayThisYear.set(Calendar.YEAR, today.get(Calendar.YEAR));
int age = today.get(Calendar.YEAR) - bday.get(Calendar.YEAR);
if(today.getTimeInMillis() < bdayThisYear.getTimeInMillis())
age--;
return age;
}
