Can you explain what an immutable class in Java is and how it is created?

An immutable class in Java is a class whose objects cannot be changed after creation. Such classes are useful for ensuring data security and multithreading.

To create an immutable class, you need to:

• Make the class final so it cannot be inherited and its behavior cannot be changed.
• Make all fields private and final.
• Do not provide setters (methods to modify fields).
• Initialize all fields through the constructor.
• If fields are mutable objects, return their copies in getters to avoid changing internal state.

Example:

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

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

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }
}