BindsAdapter

BindsAdapter is an Android library to help you create and maintain Adapter class easier via ksp( Kotlin Symbol Processing).

Installation

First, add jitpack as one of the repositories in your project.

repositories {
    maven { url 'https://jitpack.io' }
}

And then apply the ksp plugin in your module where you need the factory be generated.

plugins {
    id 'com.google.devtools.ksp' version '1.7.0-1.0.6'
}

And then declare the dependency. Do noted that for the processor dependency, it requires ksp not kapt

implementation 'com.github.Jintin.BindsAdapter:annotation:{latest-version}'
ksp 'com.github.Jintin.BindsAdapter:processor:{latest-version}'

Lastly, the generated file will be located inside build/generated/ksp/, but your IDE might not able to identify it. In such case you can add it manually like below:

sourceSets {
    main {
        java {
            srcDir "${buildDir.absolutePath}/generated/ksp/"
        }
    }
}

Usage

Adapter

First, create a abstract ListAdapter with annotation @BindAdapter and link all the associate ViewHolder into it.

@BindAdapter([MyViewHolder1::class, MyViewHolder2::class])
abstract class MyAdapter(
    diffCallback: DiffUtil.ItemCallback<String>
) : ListAdapter<String, RecyclerView.ViewHolder>(diffCallback)

Note: ListAdapter is a must now, but it doesn't mean we can't support general Adapter in the future.

ViewHolder

And then, create all your ViewHolder and label @BindFunction to the function you want to be called when onBindViewHolder is called from Adapter.

class MyViewHolder1(
    val binding: AdapterHolder1Binding,
) : RecyclerView.ViewHolder(binding.root) {

    @BindFunction
    fun bindHolder1(data: String) {
        binding.text.text = data
    }
}

Note: Using ViewBinding is a must too and there's no other options for now but we do recommend to use it.

ViewTypes

After successfully compile, the MyAdapterImpl.kt will auto-generated with the all the viewType you need like below:

public class MyAdapterImpl(
    diffCallback: DiffUtil.ItemCallback<String>,
) : MyAdapter(diffCallback) {

    public companion object {
        public const val TYPE_MY_VIEW_HOLDER1: Int = 0

        public const val TYPE_MY_VIEW_HOLDER2: Int = 1
    }
}

Note: The value and order will be the same as you declared in @BindAdapter

And you can go back to the abstract Adapter to write getItemViewType if you have multi-viewType like below:

@BindAdapter([MyViewHolder1::class, MyViewHolder2::class])
abstract class MyAdapter(
    diffCallback: DiffUtil.ItemCallback<String>,
) : ListAdapter<String, RecyclerView.ViewHolder>(diffCallback) {

    override fun getItemViewType(position: Int): Int {
        return if (position % 2 == 0) {
            MyAdapterImpl.TYPE_MY_VIEW_HOLDER1
        } else {
            MyAdapterImpl.TYPE_MY_VIEW_HOLDER2
        }
    }
}

Parameter

In real world you might want to pass value from Adapter to ViewHolder. If you want to achieve this just label the parameter with the same Annotation from both side than we will help you to link them together. For Adapter, please add parameter in constructor. For ViewHolder, you can choose either constructor or the bind function which has @BindFunction.

@Retention(AnnotationRetention.SOURCE)
@Target(AnnotationTarget.VALUE_PARAMETER)
annotation class BindListener

@BindAdapter([MyViewHolder1::class, MyViewHolder2::class])
abstract class MyAdapter(
    diffCallback: DiffUtil.ItemCallback<String>,
    @BindListener val listener: (String) -> Unit,
) : ListAdapter<String, RecyclerView.ViewHolder>(diffCallback)

class MyViewHolder1(
    private val binding: AdapterHolder1Binding,
) : RecyclerView.ViewHolder(binding.root) {

    @BindFunction
    fun bindHolder1(data: String, @BindListener listener: (String) -> Unit) {
        binding.text.text = data
        binding.root.setOnClickListener { listener.invoke(data) }
    }
}

class MyViewHolder2(
    @BindListener val listener: (String) -> Unit,
    val binding: AdapterHolder2Binding,
) : RecyclerView.ViewHolder(binding.root) {

    @BindFunction
    fun bindHolder2(String, data: String) {
        binding.text.text = data
        binding.root.setOnClickListener { listener.invoke(data) }
    }
}

Note: There's not type restriction for the parameter and we also don't force them to be equal, but it will compile fail if it can't match.

Contributing

It's an interesting project to me and it's also in very early stage for now. Any thing can be changed and any kind of contribution or participate is welcome. Feel free to ask questions or report bugs. And we're also welcome you to create new pr if you have any idea!!

License

The module is available as open source under the terms of the MIT License.