// Fig. 8.7: Date.java
// Date class declaration.

public class Date
{
    private int month; // 1-12
    private int day; // 1-31 based on month
    private int year; // any year

    private static final int[] daysPerMonth = // days in each month
        { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

        // constructor: call checkMonth to confirm proper value for month;
        // call checkDay to confirm proper value for day
        public Date( int theMonth, int theDay, int theYear )
        {
            month = checkMonth( theMonth ); // validate month
            year = theYear; // could validate year
            day = checkDay( theDay ); // validate day

            System.out.printf(
            "Date object constructor for date %s\n", this );
        } // end Date constructor

        // utility method to confirm proper month value
        private int checkMonth( int testMonth )
        {

            if ( testMonth > 0 && testMonth <= 12 ) // validate month
                return testMonth;

            else // month is invalid
                throw new IllegalArgumentException( "month must be 1-12" );
                // end method checkMonth
        }

        // utility method to confirm proper day value based on month and year
        private int checkDay( int testDay )
        {
            // check if day in range for month
            if ( testDay > 0 && testDay <= daysPerMonth[ month ] )
                return testDay;

            // check for leap year
            if ( month == 2 && testDay == 29 && ( year % 400 == 0 ||
                ( year % 4 == 0 && year % 100 != 0 ) ) )
                return testDay;

            throw new IllegalArgumentException(
                "day out-of-range for the specified month and year" );
        } // end method checkDay

        // return a String of the form month/day/year
        public String toString()
        {
            return String.format( "%d/%d/%d", month, day, year );
        } // end method toString
    } // end class Date