NullPointerException on String methods

Question

All,
I am trying to get date values on the fly and add them to my sql statement. I have a DateWorker class that provides month, day of month and year.
When I use the class in another class, I get NullPointerException. These are just plain ol' String methods, why are they giving me problems. When I run the code on its won, it works fine.
Code:
package mybeans;
import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.HashMap;
import java.util.Calendar;
public class DateWorker {
public DateWorker dateWorker;
     public DateWorker(){
          dateWorker = new DateWorker()
     public static void main(String[] args){
          String m = dateWorker.getMonth();
          String dm = dateWorker.getDayOfMonth();
          String dw = dateWorker.getDayOfWeek();
          String y = dateWorker.getYear();
          System.out.println("day of week " + dw + "<BR>");
          System.out.println("day of month" + dm + "<BR>");
          System.out.println("month " + m + "<BR>");
          System.out.println("year " + y + "<BR>");
     //get a Calendar instance.
     private Calendar cal = Calendar.getInstance();
     //gets the current month
     public String getMonth(){
     int x = cal.get(Calendar.MONTH) + 1;
     String s = String.valueOf(x);
     return s;
     //gets the current day of month
     public String getDayOfMonth(){
          int x = cal.get(Calendar.DAY_OF_MONTH);
          String s = String.valueOf(x);
          return s;
     //gets the current day of week
     public String getDayOfWeek(){
          int x = cal.get(Calendar.DAY_OF_WEEK) -1;
          String s = String.valueOf(x);
          return s;
     //gets the current year
     public String getYear(){
          int x = cal.get(Calendar.YEAR);
          String s = String.valueOf(x);
          return s;
Edited by: ink86 on Oct 8, 2007 12:57 PM

Answer 1

package mybeans;
import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.HashMap;
import java.util.Calendar;
public class DateWorker {
     public static void main(String[] args){
          DateWorker dateWorker = new DateWorker();
          String m = dateWorker.getMonth();
          String dm = dateWorker.getDayOfMonth();
          String dw = dateWorker.getDayOfWeek();
          String y = dateWorker.getYear();
          System.out.println("day of week " + dw + "<BR>");
          System.out.println("day of month" + dm + "<BR>");
          System.out.println("month " + m + "<BR>");
          System.out.println("year " + y + "<BR>");
     //get a Calendar instance.
     Calendar cal = Calendar.getInstance();
     //gets the current month
     public String getMonth(){
     int x = cal.get(Calendar.MONTH) + 1;
     String s = String.valueOf(x);
     return s;
     //gets the current day of month
     public String getDayOfMonth(){
          int x = cal.get(Calendar.DAY_OF_MONTH);
          String s = String.valueOf(x);
          return s;
     //gets the current day of week
     public String getDayOfWeek(){
          int x = cal.get(Calendar.DAY_OF_WEEK) -1;
          String s = String.valueOf(x);
          return s;
     //gets the current year
     public String getYear(){
          int x = cal.get(Calendar.YEAR);
          String s = String.valueOf(x);
          return s;
     }