Question

Define a class to represent a date. A date is defined by three properties: month (two digits), day (two digits), and year (4 digits). Include the following methods: 1) a setter function for the month to only allow numbers 1-12 2) a setter function for the day that only allows 1-31 3) a function that will print the date as month/day/year (ie 10/1/1999).

Answer 1

Answer:

The Date class below is created using Java.

1. public class Date {
3.    private int day;
4.    private int month;
5.    private int year;
7.    public Date(int d, int m, int y)
8.    {
9.        setDay(d);
10.        setMonth(m);
12.        this.year = y;
13.    }
15.    public void setMonth(int m)
16.    {
17.        if(m >= 1 && m <= 12)
18.        {
19.            this.month = m;
20.        }
21.        else
22.        {
23.            throw new IllegalArgumentException("Input Month must be between 1 - 12");
24.        }
25.    }
27.    public void setDay(int d)
28.    {
29.        if(d >=1 && d <=31)
30.        {
31.            this.day = d;
32.        }
33.        else
34.        {
35.            throw new IllegalArgumentException("Input Day must be between 1 - 31");
36.        }
37.    }
39.    public void printDate()
40.    {
41.        System.out.println(this.month + "/" + this.day + "/" + this.year);
42.    }
44. }

Explanation:

Line 1:

• Create a class and name it as Date

Line 3-5:

• Define three properties/attributes in the Date class which are day, month and year.
• The data type of the properties are defined as integer

Line 7-13:

• Create a class constructor to initialize the values for the properties (day, month and year).
• To initialize the day and month, setDay() and setMonth() setter methods are called. This is to ensure the day and month are within the range of 1-31 and 1-12, respectively.

Line 15-25:

• Create setMonth() setter method with one parameter m to accept one input value.

• The setMonth() method will check the input value m to see if it is bigger or equal to 1 and less than or equal to 31 (the valid range). If not, an error will be thrown.

Line 27 - 37:

• Create setDay() setter method with one parameter d to accept one input value.

• The setDay() method will check the input value m to see if it is bigger or equal to 1 and less than or equal to 12 (the valid range). If not, an error will be thrown.

Line 39 - 42:

• Create printDate() method to display the date as month/day/year (ie 10/1/1999)
• Use Java println() method to print the class property values, month, day, and year.
• Please note that to access the property values,  this keyword must be preceded with the property name.

Important notes:

• This program doesn't consider the valid input range of days for Feb (1 - 28 or 29) and for those of the months with only 30 days because this is not expected by the question.  
• Beside, the input year is also presumed to be a four digit number.