Question

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Design a class named MyDate. The class contains:

The Date fields year, month, and day that represent a date. month is 0-based, i.e., 0 is for January.

A no argument constructor that creates a MyDate object for the current date.

A constructor that constructs a MyDate object with a specified elapsed time since midnight, January 1, 1970, in milliseconds.

A constructor that constructs a MyDate object with the specified year, month, and day.

Three getter methods for the data fields year, month, and day, respectively.

A method named setDate(long elapsedTime) that sets a new date for the object using the elapsed time.

Implement the class and write a test program that creates two MyDate objects (using new MyDate() and new MyDate(34355555133101L)) and displays their year, month, and day.

(Hint: The first two constructors will extract the year, month, and day from the elapsed time. For example, if the elapsed time is 561555550000 milliseconds, the year is 1987, the month is 9, and day is 18. You may use the GregorianCalendar class in the java.util package, which you can use to obtain the year, month, and day of a date.)

Answer 1

import java.io.*;
import java.util.*;
public class MyDate
{
private static int[] monthLength = {31,28,31,30,31,30,31,31,30,31,30,31};
private static int[] monthOffset = {0,31,59,90,120,151,181,212,243,273,304,334};
private int leapMonth;
private int leapOffset;   
private int debugLevel = 0;
private int date;
MyDate(int year, int month, int day) throws BadDateException
{
if (debugLevel > 2) { System.out.println("MyData instance constructed with year = " + year + " month = " + month + " day = " + day); }
if ((year < 0) ||(year > 199) ||(month < 1) ||(month > 12))
{
throw new BadDateException("-->Error in Year (= " + year +") or Month (= " + month +")");
}
leapMonth = 0;
if (year%4 == 0)
{
if (year > 4)
{
leapOffset = (year-1)/4;
}
else
{
leapOffset = 0;
}
if (month == 2)
{ // Is it February?
leapMonth = 1;
}
else if (month > 2)
{ // Is it after February?
leapOffset += 1; // Can count leap day of this year.
} // Must be January, nothing else required.
}
else
{ // NOT a leap year.
leapOffset = year/4; // Leap days for all previous years, this one doesnt have one.
}
if ((day < 1) ||(day > monthLength[month-1] + leapMonth))
{
throw new BadDateException("-->Error in Day (= " + day +" where Month = " + month +")");
}
date = day + monthOffset[month-1] + leapOffset + year*365; // Actual date calculation.
}
public int getDate()
{
return date;
}
public void setDebugLevel(int dLevel)
{
debugLevel = dLevel;
}
public String toString()
{
return Integer.toString(date);
}
public int between(MyDate someOtherDate)
{
int between = Math.abs(date - someOtherDate.getDate())-1; // basic calculation.
if (between < 0) // have to watch for case where the two dates are the same.
between = 0;
return between;
}
}