import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
public class LifeAge{
    /**
     * @param birthday 日期格式y(tǒng)yyy-MM-dd
     *                 根據(jù)用戶生日計算年齡
     *                 用Calender對象取得當(dāng)前日期對象--從對象中分別取出年月日
     *                 輸出結(jié)果 例如 26歲7月零9天
     */
    public static String getAgeByBirth(String birthday) {
        //從Calendar對象中或得一個Date對象
        Calendar now = Calendar.getInstance();
        /*把出生日期放入Calendar類型的bir對象中，進(jìn)行Calendar和Date類型進(jìn)行轉(zhuǎn)換*/
        Calendar bir = Calendar.getInstance();
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
        try {
            bir.setTime(simpleDateFormat.parse(birthday));
        } catch (ParseException e) {
            e.printStackTrace();
        }
        //如果生日大于當(dāng)前日期，則拋出異常：出生日期不能大于當(dāng)前日期
        if (now.before(birthday)) {
            throw new IllegalArgumentException("The birthday is before Now,It's unbelievable");
        }
        //取出當(dāng)前年月日
        int yearNow = now.get(Calendar.YEAR);
        int monthNow = now.get(Calendar.MONTH) + 1;
        int dayNow = now.get(Calendar.DAY_OF_MONTH);
        //取出出生年月日
        int yearBirth = bir.get(Calendar.YEAR);
        int monthBirth = bir.get(Calendar.MONTH) + 1;
        int dayBirth = bir.get(Calendar.DAY_OF_MONTH);
        //先day相減,不夠向month借,然后month相減,不夠向year借,最后year相減。
        int day = dayNow - dayBirth;
        int month = monthNow - monthBirth;
        //年齡是當(dāng)前年減去出生年
        int year = yearNow - yearBirth;
        if (day < 0) {
            month -= 1;
            now.add(Calendar.MONTH, -1);//得到上一個月，用來得到上個月的天數(shù)。
            //借一個月
            day = day + now.getActualMaximum(Calendar.DAY_OF_MONTH);
        }
        if (month < 0) {
            //一年12個月,借12個月
            month = (month + 12) % 12;
            //借了12個月,少一年
            year--;
        }
        StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append(year + "歲");
        stringBuilder.append(month + "月");
        if (day < 20) {
            stringBuilder.append("零" + day + "天");
        } else {
            stringBuilder.append(day + "天");
        }
        if (year == 0 && month == 0 && day == 0) {
            stringBuilder.delete(0, stringBuilder.length());
            stringBuilder.append("今日出生");
        }
        return stringBuilder.toString();
    }
    /*main方法測試*/
    public static void main(String[] args) {
        String birthday = "1993-10-18";
        String age = getAgeByBirth(birthday);
        System.out.print("年齡=" + age);
    }
}

輸出結(jié)果

26歲7月零9天

再來一個Kotlin版

import java.text.SimpleDateFormat
import java.util.*
class LifeAge {
    /**
     * @param birthday 日期格式y(tǒng)yyy-MM-dd
     * 根據(jù)用戶生日計算年齡
     * 用Calender對象取得當(dāng)前日期對象--從對象中分別取出年月日
     * 輸出結(jié)果 例如 26歲9個月零28天
     */
     fun getAgeByBirth(birthday: String?): String {
        //從Calendar對象中或得一個Date對象
        val now = Calendar.getInstance()
        /*把出生日期放入Calendar類型的bir對象中，進(jìn)行Calendar和Date類型進(jìn)行轉(zhuǎn)換*/
        val bir = Calendar.getInstance()
        val simpleDateFormat = SimpleDateFormat("yyyy-MM-dd")
        bir.time = simpleDateFormat.parse(birthday)
        //如果生日大于當(dāng)前日期，則拋出異常：出生日期不能大于當(dāng)前日期
        require(!now.before(birthday)) { "The birthday is before Now,It's unbelievable" }
        //取出當(dāng)前年月日
        val yearNow = now[Calendar.YEAR]
        val monthNow = now[Calendar.MONTH] + 1
        val dayNow = now[Calendar.DAY_OF_MONTH]
        //取出出生年月日
        val yearBirth = bir[Calendar.YEAR]
        val monthBirth = bir[Calendar.MONTH] + 1
        val dayBirth = bir[Calendar.DAY_OF_MONTH]
        //先day相減,不夠向month借,然后month相減,不夠向year借,最后year相減。
        var day = dayNow - dayBirth
        var month = monthNow - monthBirth
        //年齡是當(dāng)前年減去出生年
        var year = yearNow - yearBirth
        if (day < 0) {
            month -= 1
            now.add(Calendar.MONTH, -1) //得到上一個月，用來得到上個月的天數(shù)。
            //借一個月
            day += now.getActualMaximum(Calendar.DAY_OF_MONTH)
        }
        if (month < 0) {
            //一年12個月,借12個月
            month = (month + 12) % 12
            //借了12個月,少一年
            year--
        }
        val stringBuilder = StringBuilder()
        stringBuilder.append(year.toString() + "歲")
        stringBuilder.append(month.toString() + "月")
        if (day < 20) {
            stringBuilder.append("零" + day + "天")
        } else {
            stringBuilder.append(day.toString() + "天")
        }
        if (year == 0 && month == 0 && day == 0) {
            stringBuilder.delete(0, stringBuilder.length)
            stringBuilder.append("今日出生")
        }
        return stringBuilder.toString()
    }
}
/*main方法測試*/
fun main() {
    val birthday = "1994-10-18"
    val age = LifeAge().getAgeByBirth(birthday)
    print("年齡=$age")
}