最近在写项目的时候遇到了一个需要根据出生日期计算年龄的问题，今天特意将代码记下来已被后期使用。
1 //根据出生日期计算年龄
2 public int getAgeByBirth(String birthDayStr) {
3 SimpleDateFormat sdf = new SimpleDateFormat( "yy-MM-dd" );
4 Date birthDay= null;
5 try {
6 birthDay = sdf.parse(birthDayStr);
7 } catch (ParseException e) {
8 e.printStackTrace();
9 }
10 // String str = sdf.format(parse( " 2005-06-09 00:00:00 " );
11
12
13 int age = 0;
14 Calendar cal = Calendar.getInstance();
15 if (cal.before(birthDay)) { //出生日期晚于当前时间，无法计算
16 throw new IllegalArgumentException(
17 "The birthDay is before Now.It's unbelievable!");
18 }
19 int yearNow = cal.get(Calendar.YEAR); //当前年份
20 int monthNow = cal.get(Calendar.MONTH); //当前月份
21 int dayOfMonthNow = cal.get(Calendar.DAY_OF_MONTH); //当前日期
22 cal.setTime(birthDay);
23 int yearBirth = cal.get(Calendar.YEAR);
24 int monthBirth = cal.get(Calendar.MONTH);
25 int dayOfMonthBirth = cal.get(Calendar.DAY_OF_MONTH);
26 age = yearNow - yearBirth; //计算整岁数
27 if (monthNow <= monthBirth) {
28 if (monthNow == monthBirth) {
29 if (dayOfMonthNow < dayOfMonthBirth) age--;//当前日期在生日之前，年龄减一
30 } else {
31 age--;//当前月份在生日之前，年龄减一
32 }
33 }
34 return age;
35 }
在调用的时候注意：
//根据修改过的出生日期从新计算被保险人的年龄tSaveLPInsuredSchema.setAge(String.valueOf(getAgeByBirth(mLPInsuredSchema.getBirthDay())));