Chapter 4, Problem 19STE

Write a better version of the method dateOK with three int parameters (Display 4.9). This version should check for the correct number of days in each month and should not just allow 31 days in any month. It will help to define another helping method named leapYear, which takes an int argument for a year and returns true if the year is a leap year. February has 29 days in leap years and only 28 days in other years. Use the following rule for determining if the year is a leap year: A year is a leap year if it is divisible by 4 but is not divisible by 100, or if it is divisible by 400.