Why do programmers create immutable classes and what problem does it solve?

Immutable (immutable) classes are created to ensure data safety and predictability. Such objects cannot be changed after creation, which helps avoid errors related to unintentional state modification, especially in multithreaded applications.

Advantages:

• Thread safety without additional synchronization.
• Simplified debugging and testing.
• Ability to use objects as keys in collections (e.g., in HashMap).

Example in Java:

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

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

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }
}

Here, the Person class is immutable: fields are final, there are no setters, and the class is declared final to prevent inheritance and behavior modification.