CompositionAdapter

A composition Recycler-View adapter kotlin implementation inspired from the post here

The library reduces the boiler plate required to write a recyclerview adapter with multiple viewTypes.

Download from repository

This library can be downloaded from repository by adding the following into Android studio gradle file.

allProjects {
  repositories {
    maven { url 'https://jitpack.io' }
  }
}
dependencies {
  compile "com.github.ksughosh:CompositionAdapter:${latest_version}"
}

The latest_version can be found under releases

Concept and working

The view types are handled as individual views and views are encapsulated within a delegate class that implements all the recycler view methods. This would make each View encapsulated as a delegate with the recyclerview adapter. This is also a data driven approach so view modelling can be handled directly with data.

Every model class should be of type ListItem the example represents:

data class ModelForViewOne(isFeatured: Boolean, isTriggered: Boolean, title: String): ListItem

data class ModelForViewTwo(showTextView: Boolean, hideButton: Boolean, titleText: String): ListItem

Every on of these data classes must have an adjoining view class to which it is bound:

class MyLinearLayoutRecyclerViewItem(context: Context?) : BaseLinearHolder<ModelForViewOne>(context){
  init{
    // inflate layout id
    setView(R.layout.element_item_my_linear_layout)
  }
  override onDataReady(data: ModelForViewOne){
    // manipulate view from data
    myTitleTextView?.text = data.titleText
    myContentTextView?.text = data.contentText
  }
}

or

class MyConstraintRecyclerViewItem(context: Context?): BaseConstraintHolder<ModelForViewTwo>(context) {
  init{
    // inflate layout id
    setView(R.layout.element_item_my_relative_layout)
  }

  override onDataReady(data: ModelForViewTwo){
    // manipulate view from data
    myTextView?.text = data.titleText

    Glide.with(this).load(data.imageUrl).into(myImageView)  // load from Glide or Picasso
  }
}

There are multiple available BaseHolder classes that would facilitate the construction of the composition adapter. Individual ViewDelegates are created with two parameters. First parameter is a lambda that returns a view and the second parameter is also a lambda that returns the condition to evaluate for the viewType. Finally, add the individual view delegates as part of the DataAdapter class that initializes the RecyclerView's adapter as shown:

class ExampleActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        // p0: view, p1: condition for the view to be shown on recyclerview
        // show MyLinearLayoutRecyclerViewItem item when the data 
        // in the list provided is of type ModelForViewOne
        val delegateOne = ViewDelegate({ MyLinearLayoutRecyclerViewItem(it?.context) }, 
                                      { it is ModelForViewOne }) 
        
        // second delegate
        val delegateTwo = ViewDelegate({ MyConstraintRecyclerViewItem(it?.context) }, 
                                      { it is ModelForViewTwo }) 
        
        // delegate with condition 
        val delegateThree = ViewDelegate( { NewRecyclerViewItem1(it?.context), 
                                      { (it as? ModelForViewOne).isTriggered == false } )
        
        val delegateFour = ViewDelegate( { NewRecyclerViewItem2(it?.context), 
                                      { (it as? ModelForViewOne).isTriggered == true } )
        
        // get the items 
        val listOfItems : MutableList<ListItem> = getListItems()
        recyclerListView?.adapter = DataAdapter(listOfItems)
          .addDelegate(delegateOne, delegateTwo, delegateThree, delegateFour)
          
        recyclerListView?.layoutManager = LinearLayoutManager(this)
    }
    
    private fun getListItems(): MutableList<ListItem> {
      val list = mutableListOf<ListItem>()
      list.add(ModelForViewOne(true, false, "title"))
      list.add(ModelForViewTwo(false, true, "title2"))
      list.add(ModelForViewOne(true, false, "title"))
      list.add(ModelForViewOne(true, false, "title"))
      list.add(ModelForViewTwo(false, false, "title"))
      list.add(ModelForViewTwo(false, false, "title")) // and so on...
      return list
    }
}

In total we have 4 different recyclerview items with individual view types and all of the view handling would be done through the data in their corresponding view classes.

Licenses

Copyright [2018] [Sughosh Krishna Kumar]

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.