This is my note for Udemy lesson: Advanced Android Bootcamp 2024.

1. Add Recycler View

Create a new project and drag a recycler view component to activity_main.xml, give it id name "recyclerView".

2. Create a Layout for List Item

Name it list_item.xml, which contains a text view with id name "tvName".

3. Create a Data Class

data class Fruit(
    val name: String,
    val supplier: String
)

4. Create a Recycler View Adapt

class MyRecyclerViewAdapter(
    private val fruitsList: List<Fruit>,
    private val clickHandler: (Fruit) -> Unit
): RecyclerView.Adapter<MyViewHolder>() {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
        val layoutInflater = LayoutInflater.from(parent.context)
        val listItem = layoutInflater.inflate(R.layout.list_item, parent, false)
        return MyViewHolder(listItem, clickHandler)
    }

    override fun getItemCount(): Int {
        return fruitsList.size
    }

    override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
        holder.bind(fruitsList[position])
    }
}

class MyViewHolder(
    private val view: View,
    private val clickHandler: (Fruit) -> Unit
): RecyclerView.ViewHolder(view) {
    fun bind(fruit: Fruit) {
        val myTextView: TextView = view.findViewById<TextView>(R.id.tvName)
        myTextView.text = fruit.name

        view.setOnClickListener {
            clickHandler(fruit)
        }
    }
}

5. Edit Main Activity

class MainActivity : AppCompatActivity() {
    private val fruitsList = listOf<Fruit>(
        Fruit("Mango", "Joe"),
        Fruit("Apple", "Frank"),
        Fruit("Banana", "Tom"),
        Fruit("Guava", "Joe"),
        Fruit("Lemon", "Alex"),
        Fruit("Pear", "Joe"),
        Fruit("Orange", "Alex")
    )

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val recyclerView = findViewById<RecyclerView>(R.id.recyclerView)
        recyclerView.setBackgroundColor(Color.YELLOW)
        recyclerView.layoutManager = LinearLayoutManager(this)
        recyclerView.adapter = MyRecyclerViewAdapter(fruitsList) {
            listItemClicked(it)
        }
    }

    private fun listItemClicked(fruit: Fruit) {
        Toast.makeText(this, "Fruit is: ${fruit.name}", Toast.LENGTH_SHORT).show()
    }
}