Why are immutable classes used in programming?

Immutable classes in programming are used to create objects whose state cannot be changed after creation.

Advantages of immutable classes:

• Thread safety: Such objects can be safely used in a multithreaded environment without additional synchronization.
• Ease of understanding: Objects do not change, which simplifies debugging and predicting program behavior.
• Use as keys: Immutable objects can be safely used in collections, such as hash tables.

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 fields name and age are declared as final, and the class is declared as final, which prevents modification of the state after object creation.