What are the advantages of immutable objects?

Immutable objects have several important advantages:

• Thread safety: their state cannot be changed after creation, which eliminates issues with concurrent access in multithreaded applications.
• Ease of debugging: the object's state is fixed, making it easier to track down errors.
• Use as keys: immutable objects can be safely used in collections such as HashMap.
• Compiler and JVM optimizations: immutability allows the JVM to perform optimizations, such as caching objects.

Example in Java:

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; }
}

This class guarantees that the object will not change after creation.