Date Class Problems

[Rich Nelson]

My teacher has asked us to take the following class file, Date.java:

public class Date {
 
private int month, day, year;
 
//
// Constructors
//
 
/*
 * Date()
 *   default constructor: sets date to 1/1/2007
 */
public Date()
{
month = 1;
day = 1;
year = 2007;
}
 
/*
 * Date(m, y, d)
 *   constructor: set date to m/d/y
 *
 *   input: m, d, y - month, day and year
 */
public Date(int m, int d, int y)
{
month = m;
day = d;
year = y;
}
 
//
// Accessor Functions
//
 
/*
 * getMonth()
 * returns month field
 */
public int getMonth()
{
return month;
}
 
/*
 *  getDay()
 *  returns day field
 */
public int getDay()
{
return day;
}
 
/*
 * getYear()
 * returns year field
 */
public int getYear()
{
return year;
}
 
//
// Mutator Functions
//
 
/*
 *  setMonth(m)
 *  sets month field to m
 */
public void setMonth(int m)
{
month = m;
}
 
/*
 *  setDay(d)
 *  sets Day field to d
 */
public void setDay(int d)
{
day = d;
}
 
/*
 *  setYear(y)
 *  sets year field to y
 */
public void setYear(int y)
{
year = y;
}
 
//
// Facilitator Functions
//
 
/*
 * toString()
 * return string representation of object
 */
public String toString()
{
return month+"/"+day+"/"+year;
}
 
/*
 * isLeapYear()
 * return true if year field is a leap year
 *    false otherwise
 */
public boolean isLeapYear()
{
return (year%400 == 0 || (year%4 == 0 && year%100 != 0));
}
 
/*
 * dayInYear()
 * returns day in the year for the current
 * month/day/year of this object
 */
public int dayInYear()
{
int days = 0;
switch (month) {
case 12: days += 30;
case 11: days += 31;
case 10: days += 30;
case  9: days += 31;
case  8: days += 31;
case  7: days += 30;
case  6: days += 31;
case  5: days += 30;
case  4: days += 31;
case  3: if (isLeapYear())
days += 29;
 else
days += 28;
case  2: days += 31;
}
return days+day;
}
 
/*
 * minus(d)
 * return number of days from date d and
 * this date and
 */
public int minus(Date d)
{
if (year == d.year)
return dayInYear() - d.dayInYear();
else {
System.out.println("ERROR: minus() method only works for dates in the same year");
return 0;
}
}
}

...and create 2 private date fields, as I have already done:

private Date startdate = new Date();
private Date enddate = new Date();

He then wants us to create two constructors: one as a default constructor, and the other that accepts the start and end dates of the time period as parameters. The problem is, I don't know how I would go about creating these methods.

I have tried:

public DateSpan()
{
     startdate.setMonth(1);
     startdate.setDay(1);
     startdate.setYear(1989);
     enddate.setMonth(1);
     enddate.setDay(1);
     enddate.setYear(2007);
}

...but I get an error saying that it must return something. Maybe I'm going about this completely wrong, anyways. Could someone please shed some light on this?

[Jesper de Jong]

The class is named Date, so the constructor must also be named Date, not DateSpan. If you call it "DateSpan" then Java thinks it's a method instead of a constructor, and in a method declaration you always need to specify a return type ("void" if the method doesn't return a value).