Java Classes And Objects

What is a Class and Object in Java: A Detailed Exploration

public class House {
    int numberOfRooms;
    String colour; 
} 

House myHouse = new House();

The Integral Role of Java Classes and Objects in Computer Programming

• Code reusability: You can reuse classes to create multiple objects, reducing code duplication and increasing efficiency.
• Organised program structure: Classes can contain other classes and objects, making it possible to create complex, yet well-organised program structures.
• Data abstraction: By encapsulating data within classes and using objects to interact with that data, you ensure a high level of data abstraction.

Class Object and Methods in Java: Fostering Interactive Programming

public class Dog {
    void bark() {
        System.out.println("The dog barks!");
    }
}

Dog myDog = new Dog();
myDog.bark();  // Outputs: The dog barks!

How Java Classes and Objects Are Structured: An In-depth Study

The Interplay of Classes, Objects, and Constructors in Java

public class Car {
    int speed;

    // Non-parameterised constructor
    Car() {
        speed = 0;
    }

    // Parameterised constructor
    Car(int startSpeed){
        speed = startSpeed;
    }
}

Engaging with Class and Object in Java with Example

public class Student {
    String name;
    int age;
    String university;

    // Constructor
    Student(String name, int age, String university) {
        this.name = name;
        this.age = age;
        this.university = university;
    }

    // Method to display Student information
    void display(){
        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
        System.out.println("University: " + university);
    }
}

Student john = new Student("John", 20, "Oxford");
john.display();  

// Output: 
// Name: John
// Age: 20
// University: Oxford

Creating Classes and Objects in Java: A Practical Approach

• Declaration: Start by declaring the class using the class keyword.
• Instance Variables: Inside the class, declare the variables that each object of the class will possess.
• Class Constructor: Declare the constructor of the class, a critical method used to initialize the variables of the object when it is created.
• Methods: Declare the methods that can perform the appropriate actions on the object's data.

 ClassName objectName = new ClassName(); 

 Vehicle myCar = new Vehicle(); 

Types of Java Classes and Objects: A Comprehensive Classification

Unpacking The Difference Between Class and Object in Java

Reviewing Different Types of Java Classes and Objects

• Concrete Classes: Typical classes in Java that can be directly instantiated with the use of the 'new' keyword.
• Abstract Classes: Cannot be directly instantiated. Instead, these classes serve as a template for other classes.
• Interface Classes: Purely abstract class types that define abstract methods. They act as a contract for classes to follow.
• Final Classes: These types of classes cannot be subclassed, serving as an extra layer of security to prevent other classes from inheriting it.

• Mutable Objects: Objects in this category have their state or value that can be changed after they are created.
• Immutable Objects: Unlike mutable objects, once you create these objects, you cannot change their state or value.

Class Object and Methods in Java: A Study in Varieties

• Standard Methods: These are regular Java methods defined inside a class.
• Constructor Methods: Special methods invoked when an object is created. Their name must match the class name, and they don't return any value.
• Getter and Setter Methods: Employed to view and modify the private variables of a class.
• Static Methods: Bound with the class, not objects of the class, and can be accessed without creating an object.

Practical Applications of Java Classes And Objects

Case Study: Implementing Classes Objects and Constructors in Java

public class Book {
    String title;
    String author;
    int ISBN;
}

Book book1 = new Book();
book1.title = "The Great Gatsby";
book1.author = 'F. Scott Fitzgerald';
book1.ISBN = 123456789;

Book book2 = new Book();
book2.title = 'War and Peace';
book2.author = 'Leo Tolstoy';
book2.ISBN = 987654321;

Book book3 = new Book();
book3.title = 'Pride and Prejudice';
book3.author = 'Jane Austen';
book3.ISBN = 741852963;

public class Book {
    String title;
    String author;
    int ISBN;

    // Constructor to initialise Book class variables
    Book(String t, String a, int i) {
        title = t;
        author = a;
        ISBN = i;
    }
}

Book book1 = new Book("The Great Gatsby", 'F. Scott Fitzgerald', 123456789);
Book book2 = new Book('War and Peace', 'Leo Tolstoy', 987654321);
Book book3 = new Book('Pride and Prejudice', 'Jane Austen', 741852963);

Practical Insights: Using Class and Object in Java with Example

public class BankAccount {
    String accountNumber;
    String accountHolder;
    double balance;

    // Constructor
    BankAccount(String number, String holder, double initialBalance) {
        this.accountNumber = number;
        this.accountHolder = holder;
        this.balance = initialBalance;
    }

    // Method to deposit money
    void deposit(double amount) {
        this.balance += amount;
    }

    // Method to withdraw money
    void withdraw(double amount) {
        if(this.balance >= amount) {
            this.balance -= amount;
        } else {
            System.out.println("Insufficient balance");
        }
    }
}

BankAccount account1 = new BankAccount("01", "Alice", 500.0);
BankAccount account2 = new BankAccount("02", "Bob", 1000.0);

Exploring Real-life Examples of Creating Classes and Objects in Java

public class Player {
    String name;
    int score;

    // Constructor
    Player(String name) {
        this.name = name;
        this.score = 0;
    }

    // Method to make a move
    void makeMove() {...}
}

Player player1 = new Player("X");
Player player2 = new Player("O");