What changes have occurred in class creation between Kotlin and Java?

Main differences between Kotlin and Java when creating classes:

• Syntax: Kotlin has a more concise and expressive syntax for defining classes.
• Primary Constructor: Kotlin allows defining a constructor directly in the class header.
• Data Classes: Kotlin provides a special class type for storing data with automatic generation of equals(), hashCode(), toString(), copy(), and componentN().
• Sealed Classes: Kotlin supports a restricted class hierarchy, preventing subclassing outside a specific package.
• Delegation: Kotlin has native support for property and interface delegation.
• Null Safety: Kotlin introduces a strict type system for null handling, preventing NPE.

Comparison table:

Feature	Kotlin	Java
Class declaration	class MyClass (val property: Type)	class MyClass { Type property; }
Primary constructor	In the class header	Separate method
Data Class	Native support (data class)	Requires manual implementation / Lombok
Sealed Class	Native support (sealed class)	Not supported
Delegation	Native support (by)	Requires manual implementation
Null Safety	Strict type system for null	Allows implicit nulls

Example of a Data Class in Kotlin:

data class User(val name: String, val age: Int)

Equivalent class example in Java (without additional libraries):

public class User {
    private final String name;
    private final int age;

    public User(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        User user = (User) o;
        return age == user.age && Objects.equals(name, user.name);
    }

    @Override
    public int hashCode() {
        return Objects.hash(name, age);
    }

    @Override
    public String toString() {
        return "User{" +
               "name='" + name + '\'' +
               ", age=" + age +
               '}';
    }
}