Java – How to convert a java.sql.Date object into a GregorianCalendar

calendardategregorian-calendarjava

I thought I'd be able to create a GregorianCalendar using the constructor that takes the year, month, and day, but I can't reliably get those fields from an instance of the java.sql.Date class. The methods that get those values from java.sql.Date are deprecated, and the following code shows why they can't be used:

import java.sql.Date;
import java.util.Calendar;
import java.util.GregorianCalendar;

public class DateTester {

    public static void main(String[] args) {
        Date date = Date.valueOf("2011-12-25");
        System.out.println("Year: " + date.getYear());
        System.out.println("Month: " + date.getMonth());
        System.out.println("Day: " + date.getDate());
        System.out.println(date);

        Calendar cal = new GregorianCalendar(date.getYear(), date.getMonth(), date.getDate());
        System.out.println(cal.getTime());
    }
}

Here's the output, showing that the month and year are not returned correctly from the deprecated getYear() and getMonth() methods of Date:

Year: 111
Month: 11
Day: 25
2011-12-25
Thu Dec 25 00:00:00 EST 111

Since I can't use the constructor that I tried above, and there's no GregorianCalendar constructor that just takes a Date, how can I convert a java.sql.Date object into a GregorianCalendar?

Best Solution

You have to do this in two steps. First create a GregorianCalendar using the default constructor, then set the date using the (confusingly named) setTime method.

import java.sql.Date;
import java.util.Calendar;
import java.util.GregorianCalendar;

public class DateTester {

    public static void main(String[] args) {
        Date date = Date.valueOf("2011-12-25");
        System.out.println(date);

        Calendar cal = new GregorianCalendar();
        cal.setTime(date);
        System.out.println(cal.getTime());
    }
}

Here's the output:

2011-12-25
Sun Dec 25 00:00:00 EST 2011