CODEWITHSUNDEEP
androidinheritancekotlin
user3057944
user3057944

Reputation: 711

Kotlin do not call super

I have a class that extends another, but in this class I do not want to call the super constructor. How can I solve it?

Here is a snipet of my code

class SubarticlePagerAdapter(fragmentManager: FragmentManager, context: Context, var selectedArticleName: String) : ArticlePagerAdapter(fragmentManager, context) {

    var subarticleDao: ArticleDao
    var itemCount = 0

    init {
        ApplicationHelper().getApplication(context).appComponent.inject(this)
        subarticleDao = ApplicationHelper().getApplication(context).subarticleDaoSession.articleDao
        initBundles(context)
    }

    override fun initBundles(context: Context?) {
        }
    }

My problem, when this constructor is called, parent class constructor run first, and initBundles() will be called from there, but at that time subarticleDao and selectedArticleName are not set and I get exception.

Upvotes: 2

Views: 1514

Answers (1)

greyhairredbear
greyhairredbear

Reputation: 802

TL;DR

I'd advise you to move the code from the init block to the initBundles function and use your variables there after initialization. Then there would be no need to avoid calling the superclasses constructor.

Extensive Answer

I think you should think about what you want to do with your design. Working around the idioms of a language is not very often a good idea or a sign of good design - at least when kotlin is your language :)

What you did with your code (overriding a - possibly abstract - method, initBundles from your superclass is pretty much the template method pattern. So it seems to me the purpose of initBundles is to let subclasses customize parts of the initialization... What basically is what you do in your init block.

EDIT: As Paul pointed out in the comments, you can't use the member selectedArticleName before your base classes initialization has finished. So if the base class calls initBundles during its initialization, then properties in the subclass won't be initialized as also stated at Paul's link.

Since in the snippet you don't use selectedArticleName, you could just move your initialization stuff to the initBundles function and init your subarticleDao there.

However, if you need to use your subclasses properties at that point, I'd really advise you to rethink your design. There should be several ways to solve this, but to decide what would suits your requirements best one would need further insight into the intentions you have with your design.

Upvotes: 2

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