AdapterDelegates Kotlin DSL

AdapterDelegateDslExample.kt

/**
 * Let's say we want to display a list of Animals in a RecyclerView. 
 * The list can contain items of type Dog, Cat and Snake.
 */

// AdapterDelegate for Dog.
fun dogAdapterDelegate(picasso : Picasso) = adapterDelegate<Dog, Animal>(R.layout.item_dog){ // Generics Types means this AdapterDelegate is used if item is instanceof Dog (whole list is List<Anmial>)
   // this block is run once in onCreateViewHolder. Think of it as an intializer for a ViewHolder.
  val name = findViewById(R.id.name)
  val image = findViewById(R.id.image)

  bind {
    // This method is called every time onBindViewHolder is called
    name.text = item.text  // item is set to the current bound item from List<Animal>. Item is of type Dog.
    picasso.load(item.image.url).into(image)
  }
}

// AdapterDelegate for Cat which uses kotlin android extensions by using adapterDelegateLayoutContainer() instead of adapterDelegate()
fun catAdapterDelegate( catClicked : (Cat) -> Unit) = adapterDelegateLayoutContainer<Cat, Animal>(R.layout.item_cat){ // Generics Types means this AdapterDelegate is used if item is instanceof Cat (whole list is List<Anmial>)
   
    // this block is run once in onCreateViewHolder. Think of it as an intializer for a ViewHolder.
  
    name.setOnClickListener {  // name is imported from kotlinx.android.synthetic.main.item_cat.* if you use kotlin android extensions
      catClicked(item) // item is set to the current bound item from List<Animal>. Item is of type Cat.
    } 
  
    bind {
      // This method is called every time onBindViewHolder is called
      
      name.text = item.name // item is bound automatically to the current item in the List<Animal>. Item is of type Cat.
      catBreed.text = item.breed
    }
}

// AdapterDelegate for Snake
fun snakeAdapterDelegate() = adapterDelegateLayoutContainer(R.layout.item_snake) {
  
  bind {
    name.text = item.name
    age.text = item.age.toString()
    age.setTextColor( 
      getColor( // convenience method / shortcut for context.getColor(id). It's part of the DSL.
        if (item.age < 3)
          R.color.snake_young
        else
          R.color.snake_old
      )
    )
  }
}

AnimalsActivity.kt

class AnimalsActivity : Activity() {
 
  overrid onCreate(b : Bundle?){
    super(b)
    setContentView(R.layout.activity_animal)
    val recyclerView = findViewById<RecyclerView>(R.id.recycler_view)
    
    // Setup the adapter with the AdapterDelegates we have defined above.
    val adapter = ListDelegationAdapter(
      dogAdapterDelegate( Picasso.get() ),
      catAdapterDelegate( this::onCatClicked ),
      snakeAdapterDelegate()
    )
    
    recyclerView.setAdapter(adapter)
  }    
  
  private fun onCatClicked(cat : Cat) {
    ...
  }
} 

The DSL has been added in AdapterDelegates 4.1.0

https://github.com/sockeqwe/AdapterDelegates