Date Class (Gregorian Calendar Date Implementation)

Java implementation of a Gregorian Date: validation (month lengths, leap years), comparison (before/after/equal), day difference, and next-day calculation; clean OOP API.

Author

• Name: Shimon Esterkin (SemionVlad)
• ID: *****2258
• Semester: 2023B

Overview

The Date class provides a robust implementation of date handling based on the Gregorian calendar system. It supports date validation, comparison, and calculations while handling special cases like leap years and month-specific day limits.

Class Structure

Date.java
├── Constants
│   └── Month Constants (JANUARY through DECEMBER)
├── Instance Variables
│   ├── day (private int)
│   ├── month (private int)
│   └── year (private int)
├── Helper Methods
│   ├── ifThirtyDays()
│   ├── ifThirtyOneDays()
│   ├── isLeapYear()
│   ├── verifyDate()
│   └── calculateDate()
└── Public Interface
    ├── Constructors
    ├── Getters/Setters
    ├── Comparison Methods
    └── Utility Methods

Features

1. Date Validation

   • Comprehensive date verification
   • Leap year handling
   • Month-specific day limits

2. Date Comparison

   • Equality checking
   • Before/after comparisons
   • Day difference calculation

3. Date Manipulation

   • Next day computation
   • Date copying
   • Individual component updates

Usage Examples

Creating Dates

// Create a new date
Date date1 = new Date(25, 12, 2023);

// Copy an existing date
Date date2 = new Date(date1);

// Invalid date defaults to 01/01/2000
Date invalidDate = new Date(31, 2, 2023);

Comparing Dates

// Check if one date is before another
boolean isBefore = date1.before(date2);

// Check if dates are equal
boolean areEqual = date1.equals(date2);

// Calculate days between dates
int daysDiff = date1.difference(date2);

Manipulating Dates

// Get tomorrow's date
Date tomorrow = date1.tomorrow();

// Modify date components
date1.setDay(15);
date1.setMonth(6);
date1.setYear(2024);

Technical Details

Date Validation Rules

1. Year limits: 0-9999
2. Month limits: 1-12
3. Day limits:
   • 31 days: Jan, Mar, May, Jul, Aug, Oct, Dec
   • 30 days: Apr, Jun, Sep, Nov
   • 28/29 days: Feb (leap year dependent)

Leap Year Rules

• Year divisible by 4 is a leap year
• Century years must be divisible by 400
• Examples:
  • 2000: Leap year (divisible by 400)
  • 2100: Not a leap year (divisible by 100 but not 400)
  • 2024: Leap year (divisible by 4)

Method Descriptions

Constructors

• Date(int day, int month, int year) - Creates new date
• Date(Date other) - Creates copy of existing date

Getters/Setters

• getDay(), getMonth(), getYear() - Return components
• setDay(int), setMonth(int), setYear(int) - Set components

Comparison Methods

• equals(Date) - Checks date equality
• before(Date) - Checks if date is earlier
• after(Date) - Checks if date is later
• difference(Date) - Calculates days between dates

Utility Methods

• tomorrow() - Returns next day's date
• toString() - Returns "DD/MM/YYYY" format

Implementation Notes

Error Handling

• Invalid dates in constructor default to 01/01/2000
• Invalid component updates are ignored
• All operations maintain date validity

Performance

• Basic operations are O(1)
• Date calculations optimize for common cases
• Memory efficient implementation

Requirements

• Java Development Kit (JDK)
• No external dependencies

Testing Recommendations

1. Test date validation

   • Valid dates in different months
   • Leap year dates
   • Invalid dates
   • Edge cases (year boundaries)

2. Test comparisons

   • Equal dates
   • Sequential dates
   • Dates across year boundaries

3. Test calculations

   • Day differences
   • Tomorrow calculations
   • Leap year transitions

Known Limitations

1. No time zone support
2. Limited to years 0-9999
3. No BC dates support
4. No partial date support

Future Enhancements

• Support for different calendar systems
• Extended year range
• Time zone support
• Date parsing from strings
• Date formatting options

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Created by SemionVlad for academic and portfolio purposes. This repository is intended for non-commercial, educational sharing only.