Checking for a valid date

Question

I have a program that takes a user's input from three text boxes to make a date. I need to be able to check to make sure that the day of the month is correct. For example if they enter 02/35/02 an error message should apear. I am trying to use a Calendar object to do this with but it isn't working. Here is my code:
                String strMonth = month.getText();
          int intMonth = Integer.parseInt(strMonth);
          if ( (intMonth < 1) || (intMonth > 12) ) {
               invalidDate("month",month.getText());
               month.requestFocus();
               return;
          else if(strMonth.length() == 1) {
               strMonth = "0" + strMonth;
          //Formating the year
          String strYear = year.getText();
          int intYear = Integer.parseInt(strYear);
          if (strYear.length() == 1) {
               //User entered only one digit
               strYear = "200" + strYear;
          else if(intYear > 40) {
               //User entered a year greater than 40 so must be 19??
               strYear = "19" + strYear;
          else {
               //If neither of the above then must be 20??
               strYear = "20" + strYear;
          intYear = Integer.parseInt(strYear);
//-----------RIGHT HERE IS MY PROBLEM------------------------------          
          //Check the day field using the month and year
          String strDay = day.getText();
          int intDay = Integer.parseInt(strDay);
          Calendar cal = Calendar.getInstance();
          cal.clear();
          cal.set(Calendar.MONTH,intMonth);
          cal.set(Calendar.YEAR,intYear);
          cal.set(Calendar.DAY_OF_MONTH,intDay);
          int min = cal.getMinimum(Calendar.DATE);
          System.out.println("Min Day: " + min);
//-------------The variable max is always 31----------------------          
                int max = cal.getActualMaximum(Calendar.DATE);
          System.out.println("Max Day: " + max);
          if( (intDay < min) || (intDay > max) ) {
               //User entered an invalid date
               invalidDate("day",strDay);
               day.requestFocus();
               return;
          else {
               //User entered a valid date
               if(strDay.length() == 1) {
                    strDay = "0" + strDay;
          //Everything is correct
          requestedDate = strMonth + "/" + strDay + "/" + strYear;
          System.out.println("All correct: " + requestedDate);The problem is that when I do this the variable max that I use to get the maximum day in the month is always 31. I would appreciate any help.

Answer 1

import java.util.*;
import java.text.SimpleDateFormat;
public class Test {
  public static void main(String args[]) {
    GregorianCalendar c = new GregorianCalendar();
    c.set(Calendar.MONTH, 9);
    c.set(Calendar.YEAR, 2002);
    c.set(Calendar.DATE, 40);
    SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy");
    System.out.println("Date is "+sdf.format(c.getTime()));
    GregorianCalendar tmp = new GregorianCalendar();
    tmp.setTime(c.getTime());
    tmp.add(Calendar.MONTH, 1);
    tmp.set(Calendar.DATE, 1);
    tmp.add(Calendar.DATE, -1);
    System.out.println("Days="+tmp.get(Calendar.DATE));
}