Simplifying code in a class hierarchy

Question

At the top of my class hierarchy is the class Mammal. Each instance of Mammal is required to statically initialize itself. (The example is silly, I know. If you are curious, I am using Android fragments and I cannot override their constructors)

For example:

public abstract class Mammal{
    private static initialize(int a, String b, ...){
        ...
    }  
}

public class Dog extends Mammal{
    public static Dog newInstance(int a, String b, ...){
        Dog dog = new Dog();
        initialize(a, b, ...);
    }
}

public class Cat extends Mammal{
    public static Cat newInstance(int a, String b, ...){
        Cat cat = new Cat();
        initialize(a, b, ...);
        return cat;
    }
}

The classes could continue indefinitely. I have looked into calling a subclass constructor from a superclass but I cannot figure out how to apply it to a static context. Thanks in advance!

what do your initialize do that cannot be done in a consructor? — Jonatan Cloutier, Aug 25 '14 at 03:35
See [this for why I cannot override the constructor](http://stackoverflow.com/questions/9245408/best-practice-for-instantiating-a-new-android-fragment) — Daiwik Daarun, Aug 25 '14 at 03:37
do the initialize need to be static or only the newInstance? — Jonatan Cloutier, Aug 25 '14 at 03:38

score 1 · Accepted Answer · answered Aug 25 '14 at 03:43

1

The initialize method should have a the a Mammal as parameter to initialize it's data from the other parameters:

  private static initialize(Mammal mammal, int a, String b, ...){
     mammal.setA(a)
     // ...
 }

answered Aug 25 '14 at 03:43

Jonatan Cloutier

899
9
26

score 1 · Answer 2 · edited May 23 '17 at 11:57

From Oracle Java Docs

If a subclass defines a static method with the same signature as a static method in the superclass, then the method in the subclass hides the one in the superclass.

It is better explained at here Overriding vs Hiding Java - Confused

To access child class's method you need to call the method with reference of the subclass

Mamal mamal = new Dog();
mamal.initialize(..) // method of super class
((Dog)mamal).initialize(...)// method of class dog

Simplifying code in a class hierarchy

2 Answers2