I am using CardView in RecyclerView for displaying a list of City names.

Along with the city name, I would like to add a curved square image containing a random background colour and the starting letter of the city name, just like the default image of our Gmail accounts.

I have tried the following approach for generating a random index in the colours array and passing the colour to the ViewHolder class of my CustomAdapter.

colors.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="purple_200">#FFBB86FC</color>
    <color name="purple_500">#FF6200EE</color>
    <color name="purple_700">#FF3700B3</color>
    <color name="teal_200">#FF03DAC5</color>
    <color name="teal_700">#FF018786</color>
    <color name="black">#FF000000</color>
    <color name="white">#FFFFFFFF</color>

    <string-array name="allColors">
        <item>#99cc00</item>
        <item>#33b5e5</item>
        <item>#0099cc</item>
        <item>#547bca</item>
        <item>#aa66cc</item>
        <item>#9933cc</item>
        <item>#669900</item>
        <item>#aeb857</item>
        <item>#cc0000</item>
        <item>#df5948</item>
        <item>#ff4444</item>
        <item>#ae6b23</item>
        <item>#ff8800</item>
        <item>#e5ae4f</item>
        <item>#ffbb33</item>
        <item>#cccccc</item>
        <item>#888888</item>
    </string-array>

</resources>

CustomAdapter.kt

package com.x.y.z
import android.graphics.Color
import android.view.LayoutInflater
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import com.x.y.z.databinding.CityCardviewActivityBinding
import com.x.y.z.models.LocationWeather
import com.x.y.z.models.LocationWeatherItem
import kotlin.random.Random


class CustomAdapter(private val allLocationslist : LocationWeather, private val onClickCallback :  (LocationWeatherItem) -> Unit) : RecyclerView.Adapter<CustomAdapter.ViewHolder>() {

    class ViewHolder(private val binding: CityCardviewActivityBinding) : RecyclerView.ViewHolder(binding.root) {

        fun bind(get: LocationWeatherItem, color: Int) {
            binding.city.text = get.city
            binding.firstLetter.text = get.city[0].toString()
            binding.roundCardView.setCardBackgroundColor(color)
        }

    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val itemView = CityCardviewActivityBinding.inflate(LayoutInflater.from(parent.context), parent, false)
        return ViewHolder(itemView)
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {

        val idx = (0 until arrayOf(R.array.allColors).size).random()
        holder.bind(allLocationslist[position], arrayOf(R.array.allColors)[idx])
        holder.itemView.setOnClickListener { v ->
            onClickCallback.invoke(allLocationslist[position])
        }

    }

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

I just generated a random index using the below method and passed the value at that index to the ViewHolder Class.

val idx = (0 until arrayOf(R.array.allColors).size).random()

But the background colour for all the CardViews is the same when run.

I have just started my journey in Android and am not able to figure out the mistake. I kindly request our community members to share their valuable insights. Thank you.

CodePudding user response：

arrayOf(R.array.allColors) gives you a list containing only one item which is the id for allColors. You can use this to get the list of the colors

val randomColor = resources.getStringArray(R.array.exo_playback_speeds).random()

CodePudding user response：

R class contains resource identifiers that are just ints. So, arrayOf(R.array.allColors) is an array of just one integer which is a resource id and not any of your color values.

To access array resources, replace arrayOf(R.array.allColors) with something like resources.getIntArray(R.array.allColors).

CodePudding user response：

First of all in color.xml define your colors and create array of it.

<?xml version="1.0" encoding="utf-8"?>
<resources>

<item name="blue" type="color">#FF33B5E5</item>
<item name="purple" type="color">#FFAA66CC</item>
<item name="green" type="color">#FF99CC00</item>
<item name="orange" type="color">#FFFFBB33</item>
<item name="red" type="color">#FFFF4444</item>
<item name="darkblue" type="color">#FF0099CC</item>
<item name="darkpurple" type="color">#FF9933CC</item>
<item name="darkgreen" type="color">#FF669900</item>
<item name="darkorange" type="color">#FFFF8800</item>
<item name="darkred" type="color">#FFCC0000</item>

<integer-array name="androidcolors">
    <item>@color/blue</item>
    <item>@color/purple</item>
    <item>@color/green</item>
    <item>@color/orange</item>
    <item>@color/red</item>
    <item>@color/darkblue</item>
    <item>@color/darkpurple</item>
    <item>@color/darkgreen</item>
    <item>@color/darkorange</item>
    <item>@color/darkred</item>
</integer-array>

</resources>

Now generate random color like below in onCreate method.

int[] androidColors = getResources().getIntArray(R.array.androidcolors);
int randomAndroidColor = androidColors[new Random().nextInt(androidColors.length)];

Lastly set this generated color.

view.setBackgroundColor(randomAndroidColor); 

Source taken from here.