Initializing final fields in Java

Question

I have a class with lots of final members which can be instantiated using one of two constructors. The constructors share some code, which is stored in a third constructor.

Answer 1

You need to make sure that in every constructor you are initializing all final variables. What I would do is have one constructor that initializes all the variables and have all the other constructor call that, passing in null or some default value if there is a field that they are not given a value for.

Example:

public class MyClass {
    private final SomeType one;
    private final SuperType two;

    //constructor that initializes all variables
    public MyClas(SomeType _one, SuperType _two) {
        one = _one;
        two = _two;
    }

    private MyClass(SomeType _one) {
        this(_one, null);
    }

    public MyClass(SomeType _one, SubTypeOne _two) {
        this(_one, _two);
    }

    public MyClass(SomeType _one, SubTypeTwo _two) {
        this(_one, _two);
    }
}