DynamicRecyclerViewAdapter

DynamicRecyclerViewAdapter is a library that abstracts out the need for creating a new recyclerViewAdapter for each of your recyclerViews. The main goal for DynamicRecyclerViewAdapter is to allow a developer to register the view holders that will be present in a recyclerView and have them be automatically created under the hood by passing in the viewHolder's associated ViewModel.

How to use

First add the library to your gradle.build file using the following line

allprojects {
    repositories {
        ...
        maven { url 'https://jitpack.io' }
    }
}
 
dependencies {
    implementation 'com.github.argallo:DynamicRecyclerViewAdapter:0.0.1'
}

Next let's create a ViewModel, DelegateCallback, and a ViewHolder:

The ViewModel should extend ViewModel and pass any properties that will need to be set on the viewHolder. Make sure to pass the associated ViewHolder::class in the parent constructor.

data class ExampleViewModel(
    val text: String
): ViewModel(ExampleViewHolder::class)

The Delegate will allow our viewHolder to make callbacks to our Activity or Fragment where we implement our delegate.

interface ExampleDelegate: Delegate {
    fun didSelectExample(index: Int)
}

Finally we create a ViewHolder class which extends ViewHolder<T>. Our generic type in this case is the ViewModel we want to associate with our viewHolder. The ViewHolder must also create a companion object that implements Factory<T>. This will allow our AdapterRecyclerView to create viewHolder instances under the hood when given a specific associated ViewModel.

class ExampleViewHolder(creator: FactoryCreator, private val delegate: ExampleDelegate? = creator.delegate as? ExampleDelegate):
    ViewHolder<ExampleViewModel>(creator.inflater, creator.parent, R.layout.example_layout) {
    companion object: Factory<ExampleViewHolder> {
        override fun create(creator: FactoryCreator): ExampleViewHolder = ExampleViewHolder(creator)
    }

    init {
        //delegate for recyclerview
        view.setOnClickListener {
           delegate?.didSelectExample(adapterPosition)
        }
    }

    override fun apply(viewModel: ExampleViewModel) {
        val textView: TextView = view.findViewById(R.id.textView)
        textView.text = viewModel.text
    }
}

Setting up our recyclerView

In this example we will create a simple recyclerView in our mainActivity.

First we want to have an objecct which consists of our Identifiers. Identifiers are just ViewHolder class types we plan to register with our AdapterRecyclerView.

class MainActivity : AppCompatActivity(), ExampleDelegate {
    object Identifiers {
        val ExampleViewHolder = ExampleViewHolder::class
    }

Next we setup our recyclerView and our dynamic adapter. *note the AdapterRecyclerView takes in a default list but can also be left empty and updated later.

    private var adapterRecyclerView = AdapterRecyclerView(mutableListOf(ExampleViewModel("Hello there!"), ExampleViewModel("Goodbye!!")))
    private lateinit var recyclerView: RecyclerView

Our on create will setup our recyclerView. We need to give it a layout and set the adapter. Here we also register our viewHolder classes and any callbacks associated with viewHolders.

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        
        recyclerView = findViewById(R.id.recyclerView)
        recyclerView.layoutManager = LinearLayoutManager(applicationContext)
        recyclerView.adapter = adapterRecyclerView

        adapterRecyclerView.registerVH(Identifiers.ExampleViewHolder)
        adapterRecyclerView.registerDelegate(Identifiers.ExampleViewHolder, this)
    }

There's a few update call's that will updated the list of ViewModels in the adapterRecyclerView and notify the recyclerview of the proper changes. This works for a specific index as well.

    fun updateViewModels(viewModels: List<ViewModel>) {
        adapterRecyclerView.updateViewModels(viewModels)
    }

    fun updateViewModelAtIndex(viewModel: ViewModel, index: Int) {
        adapterRecyclerView.updateViewModelAtIndex(viewModel, index)
    }

Finally, our Activity implements the ExampleDelegate interface so we need to provide the implementation for its functions.

    override fun didSelectExample(index: Int) {
        Log.d("MainActivity", "$index")
    }
}