'Android | Update RecyclerView Adapter on ViewHolder onClick

I expect my 'heart' icon to change when my ViewHolder item is clicked. Fortunately, it does this. However, an issue arises as multiple items seems to replicate the button click.

What I mean is: If I tap the heart on item number 1. Other items throughout the list replicate also change the heart. Why is this happening and what is a potential fix? I am confused why this issue is occuring as I am referencing the ViewHolder item. Thus, shouldn't it only affect the item I am clicking?

View Holder

        fun bind(item: Location) {
            heart.setOnClickListener {
                item.fav = item.fav != true
                heart.setImageDrawable(
                when (item.fav) {
                    false -> (ContextCompat.getDrawable(itemView.context, R.drawable.ic_border_heart))
                    else -> (ContextCompat.getDrawable(itemView.context, R.drawable.ic_whole_heart))
                })

            }
        }

Solution 1:^[1]

You didn't check the view ID in the onClick method. You can set onClick directly on the views as below.

    class LocationViewHolder(v: View): RecyclerView.ViewHolder(v), View.OnClickListener {

private val actLoc: TextView = v.findViewById(R.id.location_main)
private val genLoc: TextView = v.findViewById(R.id.location_subtitle)
private val heart: ImageView = v.findViewById(R.id.heart)
private lateinit var item: Location

fun bind(item: Location) {
    this.item = item
    actLoc.setText(item.actualLocation)
    actLoc.setOnClickListener {
        Toast.makeText(itemView.context, "${item.cords}", Toast.LENGTH_SHORT).show()
    }
    genLoc.setText(item.genLocation)
    genLoc.setOnClickListener {
        Toast.makeText(itemView.context, "${item.cords}", Toast.LENGTH_SHORT).show()
    }
    heart.setOnClickListener {
        item.fav = item.fav != true
        heart.setImageDrawable(
            when (item.fav) {
                false -> (ContextCompat.getDrawable(itemView.context, R.drawable.ic_border_heart))
                else -> (ContextCompat.getDrawable(itemView.context, R.drawable.ic_whole_heart))
            })

    }
}

Solution 2:^[2]

However, an issue arises as multiple items seems to replicate the button click.

it is because of the cell recycling mechanism

heart.setImageDrawable(
   when (item.fav) {
       false -> (ContextCompat.getDrawable(itemView.context, R.drawable.ic_border_heart))
       else -> (ContextCompat.getDrawable(itemView.context, R.drawable.ic_whole_heart))
})

should be part of the bind function in the viewholder and not part of the onClick function. What I would expect is

Click informs the viewmodel
Viewmodel update the dataset
Viewmodel informs the recyclerview

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1	Jennifer Karling
Solution 2	Blackbelt

'Android | Update RecyclerView Adapter on ViewHolder onClick

Solution 1:[1]

Solution 2:[2]

Sources

Related Questions

Solution 1:^[1]

Solution 2:^[2]