Java - How to add and subtract year, month and day from Date

javatime

Let's look at various ways to add a date to a Date. Since Date is a time measured based on the year 1970, date operation was performed using Calendar.

Add and subtract dates from current time

This is the code to add the month and day to the Date object that holds the current time. The current Date is set in Calendar and date operation is performed with add(). To subtract a date, simply put a negative number.

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Example {
    public static void main(String args[]) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(new Date());
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        System.out.println("current: " + df.format(cal.getTime()));

        cal.add(Calendar.MONTH, 2);
        cal.add(Calendar.DATE, -3);
        System.out.println("after: " + df.format(cal.getTime()));
    }
}

result

current: 2019-03-23
after: 2019-05-20

Add to and subtract from specific dates

Same as above, but different to generate a Date of a specific date. This time we also did date and time calculations.

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Example {
    public static void main(String args[]) {
        Calendar cal = Calendar.getInstance();
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");
        Date date = null;
        try {
            date = df.parse("2019-07-04T12:30:30+0530");
        } catch (ParseException e) {
            e.printStackTrace();
        }
        cal.setTime(date);
        System.out.println("current: " + df.format(cal.getTime()));

        cal.add(Calendar.YEAR, 1);
        cal.add(Calendar.MONTH, 2);
        cal.add(Calendar.DATE, 3);
        cal.add(Calendar.HOUR_OF_DAY , 1);
        cal.add(Calendar.MINUTE, 20);
        cal.add(Calendar.SECOND, 10);
        System.out.println("after: " + df.format(cal.getTime()));
    }
}

result

current: 2019-07-04T16:00:30+0900
after: 2020-09-07T17:20:40+0900

Add two dates

To add two dates, you need to use two calendars. You can get the date with Calendar.get. By applying the above code, you can implement it as follows. In MONTH, 0 means January (zero based), so you need to add 1 when performing calculations.

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Example {
    public static void main(String args[]) {
        Calendar cal = Calendar.getInstance();
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        try {
            cal.setTime(df.parse("2019-07-04"));
        } catch (ParseException e) {
            e.printStackTrace();
        }
        Calendar cal2 = Calendar.getInstance();
        cal2.setTime(new Date());
        System.out.println("cal: " + df.format(cal.getTime()));
        System.out.println("cal2: " + df.format(cal2.getTime()));

        cal.add(Calendar.YEAR, cal2.get(Calendar.YEAR));
        cal.add(Calendar.MONTH, cal2.get(Calendar.MONTH) + 1); // Zero-based months
        cal.add(Calendar.DATE, cal2.get(Calendar.DATE));
        System.out.println("after cal: " + df.format(cal.getTime()));
        System.out.println("after cal2: " + df.format(cal2.getTime()));
    }
}

result

cal: 2019-07-04
cal2: 2019-03-23
after cal: 4038-10-27
after cal2: 2019-03-23

Clean up

We have seen how to perform date operation on Date using Calendar.

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