Calculate age from BirthDate

Question

I have DatePicker Dialog, When I select date at that time I want to calculate age it\'s working but when I select date of current year at that time it showing the -1 age instead

Answer 1

public static String calculateAge(String strDate) {

    int years = 0;
    int months = 0;
    int days = 0;

    try {
        long timeInMillis = Long.parseLong(strDate);
        Date birthDate = new Date(timeInMillis);


        //create calendar object for birth day
        Calendar birthDay = Calendar.getInstance();
        birthDay.setTimeInMillis(birthDate.getTime());
        //create calendar object for current day
        long currentTime = System.currentTimeMillis();
        Calendar now = Calendar.getInstance();
        now.setTimeInMillis(currentTime);
        //Get difference between years
        years = now.get(Calendar.YEAR) - birthDay.get(Calendar.YEAR);
        int currMonth = now.get(Calendar.MONTH) + 1;
        int birthMonth = birthDay.get(Calendar.MONTH) + 1;

        //Get difference between months
        months = currMonth - birthMonth;


        //if month difference is in negative then reduce years by one and calculate the number of months.
        if (months < 0) {
            years--;
            months = 12 - birthMonth + currMonth;
            if (now.get(Calendar.DATE) < birthDay.get(Calendar.DATE))
                months--;
        } else if (months == 0 && now.get(Calendar.DATE) < birthDay.get(Calendar.DATE)) {
            years--;
            months = 11;
        }
        //Calculate the days
        if (now.get(Calendar.DATE) > birthDay.get(Calendar.DATE))
            days = now.get(Calendar.DATE) - birthDay.get(Calendar.DATE);
        else if (now.get(Calendar.DATE) < birthDay.get(Calendar.DATE)) {
            int today = now.get(Calendar.DAY_OF_MONTH);
            now.add(Calendar.MONTH, -1);
            days = now.getActualMaximum(Calendar.DAY_OF_MONTH) - birthDay.get(Calendar.DAY_OF_MONTH) + today;
        } else {
            days = 0;
            if (months == 12) {
                years++;
                months = 0;
            }
        }
        //adarsh
        if (currMonth > birthMonth) {
            if (birthDay.get(Calendar.DATE) > now.get(Calendar.DATE)) {
                months = months - 1;
            }
        }//---------------------------------

    } catch (Exception e) {
        e.printStackTrace();
    }
    //Create new Age object
    return years + " Y " + months + " M " + days + " days";
}

Answer 2

This is how I implement in my source code, I tested. Hope that it is useful :

public static int getAge(String dateTime, String currentFormat) {
    SimpleDateFormat dateFormat = new SimpleDateFormat(currentFormat);

    try {
        Date date = dateFormat.parse(dateTime);
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);

        int year = calendar.get(Calendar.YEAR);
        int month = calendar.get(Calendar.MONTH);
        int day = calendar.get(Calendar.DAY_OF_MONTH);


        Date currentDate = new Date();
        Calendar currentCalendar = Calendar.getInstance();
        currentCalendar.setTime(currentDate);

        int currentYear = currentCalendar.get(Calendar.YEAR);
        int currentMonth = currentCalendar.get(Calendar.MONTH);
        int currentDay = currentCalendar.get(Calendar.DAY_OF_MONTH);

        int deltaYear = currentYear - year;
        int deltaMonth = currentMonth - month;
        int deltaDay = currentDay - day;

        if (deltaYear > 0) {
            if (deltaMonth < 0) {
                deltaYear --;
            } else if (deltaDay < 0){
                deltaYear --;
            }

            return deltaYear;
        }
    } catch (java.text.ParseException e) {
        e.printStackTrace();
    }

    return 0;
}

Answer 3

 private boolean getAge(int year, int month, int day) {
    try {
        Calendar dob = Calendar.getInstance();
        Calendar today = Calendar.getInstance();
        dob.set(year, month, day);
        int monthToday = today.get(Calendar.MONTH) + 1;
        int monthDOB = dob.get(Calendar.MONTH)+1;
        int age = today.get(Calendar.YEAR) - dob.get(Calendar.YEAR);
        if (age > 18) {
            return true;
        } else if (age == 18) {
            if (monthDOB > monthToday) {
                return true;
            } else if (monthDOB == monthToday) {
                int todayDate = today.get(Calendar.DAY_OF_MONTH);
                int dobDate = dob.get(Calendar.DAY_OF_MONTH);
                if (dobDate <= todayDate) { // should be less then
                    return true;
                } else {
                    return false;
                }
            } else {
                return false;
            }
        } else {
            return false;
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    return false;
}

Answer 4

private int getAge(String dobString){

    Date date = null;
    SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
    try {
        date = sdf.parse(dobString);
    } catch (ParseException e) {
        e.printStackTrace();
    }

    if(date == null) return 0;

    Calendar dob = Calendar.getInstance();
    Calendar today = Calendar.getInstance();

    dob.setTime(date);

    int year = dob.get(Calendar.YEAR);
    int month = dob.get(Calendar.MONTH);
    int day = dob.get(Calendar.DAY_OF_MONTH);

    dob.set(year, month+1, day);

    int age = today.get(Calendar.YEAR) - dob.get(Calendar.YEAR);

    if (today.get(Calendar.DAY_OF_YEAR) < dob.get(Calendar.DAY_OF_YEAR)){
        age--;
    }



    return age;
}

Answer 5

Here is a Kotlin extension of the Date class returning the age corresponding to a Date object

val Date.age: Int
get() {
    val calendar = Calendar.getInstance()
    calendar.time = Date(time - Date().time)
    return 1970 - (calendar.get(Calendar.YEAR) + 1)
}

It is compatible for all Android versions. If you wonder what '1970' is, that's the Unix Epoch. The timestamp is 0 on January 1, 1970.

Answer 6

Here is my solution in Kotlin:

import java.time.LocalDateTime

fun getAge(birthYear: Int, birthMonth: Int, birthDay: Int): Int {
    var age: Int = LocalDateTime.now().year - birthYear
    if (birthMonth > LocalDateTime.now().monthValue || birthMonth == LocalDateTime.now().monthValue && birthDay > LocalDateTime.now().dayOfMonth) { age-- }
    if (age < 0) { age = 0 }
    return age
}