How to access another activity's XML from recyclerView adapter?

Question

This is my adapter's onBindViewHolder function:

    override fun onBindViewHolder(holder: InventoryHolder, position: Int) {
    holder.binding.inventoryImageView.setImageResource(productList.get(position).image)
    holder.binding.productTextInventory.text = "Name: ${productList.get(position).name}"
    holder.binding.equipButton.setOnClickListener{

        if(productList.get(position).type == "Background"){
            //change main menu background photo.
            println("Background")
        }
        if(productList.get(position).type == "Character"){
            //change game character.
            println("Character")

        }


    }
    holder.binding.productTypeInventoryText.text = "Type: ${productList.get(position).type}"
}

As you can see it's a basic game inventory system. I need to change activity_main.xml 's components when equipButton clicked. For example I need to change image source here:

        <ImageView
        android:id="@+id/imageView"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_row="0"
        android:layout_column="0"
        android:onClick="incScore"
        app:srcCompat="@drawable/simpson" />

How can I do this?

Answer 1

You could add lambda expression function parameter in your adapter like this

class YourAdapter(private val onClickEquip:(String) -> Unit)

in your onClickListener you could use the function like this

holder.binding.equipButton.setOnClickListener{

    if(productList.get(position).type == "Background"){
        //change main menu background photo.
        onClickEquip("Background")
        println("Background")
    }
    if(productList.get(position).type == "Character"){
        //change game character.
        onClickEquip("Character")
        println("Character")

    }
}

and in your activity when you create your adapter instance like this

val adapter = YourAdapter { type ->
        when(type){
            "Character" -> //Change image
            "Background" -> //Change image
        }
}

Answer 2

As I understand you have an Activity which contains a view with Adapter and you want to change a view which is part of Activity 's UI from that same Adapter . In order to do so you can create an interface which will be used to pass the data between both sides. Let's say your interface looks like this:

interface OnInventoryClickListener {
    fun onItemClick(type: ProductType)
}

And inside your Adapter you have a variable of type OnIventoryClickListener which the Activity will provide:

lateinit var clickListener: OnInventoryClickListener

fun setListener(listener: OnInventoryClickListener){
    clickListener = listener
}
// ... Inside your onBindViewHolder
holder.binding.equipButton.setOnClickListener{
    clickListener.onItemClick(productList.get(position).type)
}
// ...

And from your Activity just call:

// adapter is the instance of your adapter.
adapter.setListener(object: OnInventoryClickListener {
    override fun onItemClick(type: Int) {
        // Change whatever you want based on type
    }
})

And that should do the trick. I suggest you to learn more about interfaces and how you can use them.