Question

(Date Class) Create class Date with the following capabilities: a) Output the date in multiple formats, such as MM/DD/YYYY June \(14, \quad 1992\) DDD YYYY b) Use overloaded constructors to create Date objects initialized with dates of the formats in part (a). In the first case the constructor should receive three integer values. In the second case it should receive a String and two integer values. In the third case it should receive two integer values, the first of which represents the day number in the year. \([\text {Hint: }\) To convert the string representation of the month to a numeric value, compare strings using the equals method. For example, if \(s 1\) and \(s 2\) are strings, the method call s1.equals \((s 2)\) returns true if the strings are identical and otherwise returns false.

Short answer

Create a Date class with overloaded constructors for different formats and methods to output them.

Step-by-step solution

Define Class Variables

Begin by defining variables for the Date class. You will need integer variables for `day`, `month`, and `year`. Additionally, a list of strings for month names will help in handling format conversions.

Create the First Constructor

Define a constructor that takes three integer parameters: `month`, `day`, and `year`. Assign these values to the respective instance variables.

Create the Second Constructor

Define a constructor that takes a string for the month and two integer parameters for the day and year. Use a loop to compare the string month with the month names list and get the corresponding integer value for the month.

Create the Third Constructor

Define a constructor that takes two integer parameters for `dayOfYear` and `year`. Calculate the month and day from `dayOfYear`. You can do this by iterating over the days in each month, subtracting from `dayOfYear` until it is less than the days in the current month.

Write Method to Output Format MM/DD/YYYY

Implement a method `outputDate1` that returns the date in the format `MM/DD/YYYY`. Format the `month`, `day`, and `year` variables into this string format.

Write Method to Output Format Month day, YYYY

Implement a method `outputDate2` that returns the date in the format `Month day, YYYY`. Use the month names list to get the string representation of the month.

Write Method to Output Format DDD YYYY

Implement a method `outputDate3` that calculates the day of the year using `month` and `day` values. Use a loop to add days of each month until reaching the current month and add the current day. Format this into `DDD YYYY`.

Key concepts

Java programming

Java is a widely-used programming language known for its object-oriented approach. It is designed to be platform-independent, meaning Java programs can run on any device that has a Java Virtual Machine (JVM), offering great flexibility.

When working with Java, you often define classes and create objects from those classes. A class in Java is a blueprint or prototype that defines the variables and methods common to all objects of a certain kind. For example, a `Date` class can contain variables like `month`, `day`, and `year` and methods to manipulate dates.

This aligns with the core principle of encapsulation in object-oriented programming, which promotes bundling data and methods that operate on the data within one unit or class. This makes the code more modular and easier to manage.

Date handling

Handling dates in Java can be complex due to the need to accommodate various date formats. In Java, you might need to manipulate dates and display them in different formats.

The `Date` class, as described in the solution, can be constructed to allow date representation in formats like `MM/DD/YYYY`, `Month day, YYYY`, or `DDD YYYY` (day of the year). This functionality can be particularly useful in software applications that require date tracking and manipulation.

Having different constructors for a `Date` class enables the creation of date objects that can be flexibly initialized with different input formats. This is crucial for applications that might receive date input from various sources, such as user input or external systems.

Constructor overloading

Constructor overloading in Java is a technique that allows a class to have more than one constructor with different parameter lists. The signature of each overloaded constructor must differ in either the number or type of parameters.

For example, in the `Date` class, constructor overloading enables the creation of date objects using:

• Integers for `month`, `day`, and `year`
• A `String` for the month name along with integers for `day` and `year`
• An integer for `dayOfYear` and an integer for `year`

Using overloaded constructors ensures that developers can create `Date` objects from various input formats without changing the code base, improving both flexibility and reusability.

String manipulation

String manipulation is a critical concept in Java, especially while handling tasks like date formatting and conversion. Strings in Java are immutable, meaning any operation on a string returns a new string instead of modifying the original one.

In a `Date` class, string manipulation is used to convert a month name string into a numeric month value. This involves comparing the input string against a predefined list of month names, which can be efficiently done using methods like `equals()` to ensure an accurate match.

Additionally, when generating date formats such as `Month day, YYYY`, string manipulation joins month names with day and year values to form a user-friendly display. Understanding string manipulation techniques enhances a developer's ability to handle complex text processing tasks efficiently.