Java classes are the cornerstone of object-oriented programming in Java—they’re like blueprints for creating objects that combine state (fields) and behavior (methods).

🧱 Basic Class Structure

public class Dog {
    String name;
    String breed;

    // Constructor
    public Dog(String name, String breed) {
        this.name = name;
        this.breed = breed;
    }

    // Method
    public void speak() {
        System.out.println(name + " says woof!");
    }
}

• Fields (name, breed) hold data
• Constructor initializes the object when it’s created
• Methods define behavior

🐾 Creating an Object

Dog myDog = new Dog("Fido", "Labrador");
myDog.speak();  // Fido says woof!

• Use new to create an instance (object) of the class

🔐 Access Modifiers

Java uses modifiers to control visibility:

🧬 Inheritance

Classes can inherit properties and methods:

public class Puppy extends Dog {
    public void play() {
        System.out.println(name + " is playing!");
    }
}

• extends allows Puppy to inherit from Dog

💡 Other Features

• Static members: Belong to the class, not the instance
• Abstract classes: Can’t be instantiated directly—used as base classes
• Interfaces: Define contracts that a class must implement
• Encapsulation: Use private fields and public getters/setters

public class Cat {
    private String mood;

    public String getMood() {
        return mood;
    }

    public void setMood(String mood) {
        this.mood = mood;
    }
}