Final Fields

If you declare a field as final, its value cannot be changed after an instance of a class is made.

You are required to explicitly initialize final fields in the constructor.

class Muppet {
    final String name;

    Muppet(String name) {
        // Without this, it wouldn't work
        this.name = name;
    }
}

void main() {
    Muppet gonzo = new Muppet("Gonzo");
    System.out.println(gonzo.name);

    // Cannot update the .name field later
    // gonzo.name = "Gonzo, the great";
}

You can also do this directly when declaring the field.¹

class Muppet {
    // Aren't they all though?
    final boolean talented = true;
}

void main() {
    Muppet gonzo = new Muppet();
    System.out.println(gonzo.talented);
}