Re: question about the calendar class

From:

John <printdude1968@gmail.com>

Newsgroups:

comp.lang.java.help

Date:

Sat, 24 Feb 2007 14:44:04 GMT

Message-ID:

<UaYDh.650$PV3.9803@ursa-nb00s0.nbnet.nb.ca>

Knute Johnson wrote:

John T wrote:

Knute Johnson wrote:

John T wrote:

I have the following lines of code

Calendar c=null;
c.set(2007, 2, 15);

According to the API, I am invoking the set method correctly

* set(int year, int month, int date)
Sets the values for the calendar fields YEAR, MONTH, and
DAY_OF_MONTH *

http://java.sun.com/j2se/1.5.0/docs/api/index.html?java/util/Calendar.html

So why is the JVM complaining at runtime

* Exception in thread "main" java.lang.NullPointerException
at staffing.createManager.main(createManager.java:13) *

There is nothing in the API about this method throwing a NPE
exception. Can someone tell me what is wrong with my method call?

If you set the reference to a null, calling any method on it is going
to give you a NPE.

To use Calendar you need to create an instance and then set the
fields. See Calendar.getInstance() and it's many variations.

Sorry to be such a pain, but I'm trying to figure out how to convert a
Calendar reference to a String so that I can use println to display it.
Here's a bit of my code

    String hireDate;
    Calendar now = Calendar.getInstance();
    now.set(2007, 2, 15);
    // I need to convert now (Calendar) to StringhireDate=??????

It's probably pretty simple but what ever it is, is escaping me.

You can format it your self by getting the individual fields but the
Date and DateFormat classes are what you really want.

import java.text.*;
import java.util.*;

public class test7 {
    public static void main(String[] args) {
        Calendar c = Calendar.getInstance();
        c.set(2007,1,23);

        Date d = c.getTime();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy MM dd");
        System.out.println(sdf.format(d));
    }
}

Got it... but why does the second argument to c.set get translated to 2
when it is displayed? Is it the same idea as with an Array index...
starting at 0?