Random Color for each row in a list view from array of colors

Question

I am setting the background color for each row in my customadapter as

public View getView(int position, View convertView, ViewGroup parent) {





    if (inflater == null)
        inflater = (LayoutInflater) activity
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    if (convertView == null) {
        convertView = inflater.inflate(R.layout.coupon_list_row, null);
        int temp_index = ExtraFu.randInt(0, 9);
        convertView.setBackgroundColor(color_arr[temp_index]);
        Log.d("temp_index", String.valueOf(temp_index));
    }

My array of color

int color_arr[]={R.color.cred,R.color.cpink,R.color.cpurple,R.color.cdpurple,R.color.cindigo,R.color.cblue,R.color.cdorange,R.color.cgreen,R.color.cbroun,R.color.ccyan};

this is the function randInt

  public static int randInt(int min, int max) {

    // Usually this can be a field rather than a method variable
    Random rand = new Random();

    // nextInt is normally exclusive of the top value,
    // so add 1 to make it inclusive
    int randomNum = rand.nextInt((max - min) + 1) + min;

    return randomNum;
}  

the row background is set to two color. Is that the random number is generated same all the time?

Answer 1

  if (position%4 == 0){
             // set convertView Background          
        } else if (position%4 == 1){
            // set convertView Background  
        } else if (position%4 == 2){
            // set convertView Background  
        } else if (position%4 == 3){
            // set convertView Background  
        }

This will randomly generate the four different color in your listview.

inside adapter

  @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            convertView = lv.inflate(res, null);
            holder = new ViewHolder();
            holder.textView = (TextView)convertView.findViewById(R.id.text);
            convertView.setTag(holder);

        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        if (position%4 == 0){
            holder.textView.setBackgroundColor(Color.parseColor("#1e86cf"));
        } else if (position%4 == 1){
            holder.textView.setBackgroundColor(Color.parseColor("#2ca0ea"));
        } else if (position%4 == 2){
            holder.textView.setBackgroundColor(Color.parseColor("#2cc4ea"));
        } else if (position%4 == 3){
            holder.textView.setBackgroundColor(Color.parseColor("#2ceae3"));
        }
        return convertView;
    }

ViewHolder Class:

    class ViewHolder{
        public TextView textView;
    }

adapter custom layout :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
    android:id="@+id/text"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center"
    android:padding="15dp"
    android:textColor="@color/white"
    android:textSize="20sp"
    android:textStyle="bold"/>
</LinearLayout>

Answer 2

Use Below code to get Random colors

Random rnd = new Random();
        int color = Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));
        convertView.setBackgroundColor(color);

Answer 3

I have edited your code

you need to use below line i have checked its working finr for my layout

 convertView.setBackgroundResource(color_arr[rnd]);

Your updated code not checked on my side

if (inflater == null)
        inflater = (LayoutInflater) activity
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    if (convertView == null) {
        convertView = inflater.inflate(R.layout.coupon_list_row, null);



 int color_arr[]=  {R.color.cred,R.color.cpink,R.color.cpurple,R.color.cdpurple,R.color.cindigo,R.color.cblue,R.color.cdorange,R.color.cgreen,R.color.cbroun,R.color.ccyan};
int rnd = new Random().nextInt(color_arr.length);


        //convertView.setBackgroundColor(color_arr[temp_index]);

        convertView.setBackgroundResource(color_arr[rnd]);

    }

Reference Code is which i have tried and works fine so do the needful changes

int color_arr[] = {R.color.colorAccent, R.color.colorPrimary, R.color.colorPrimaryDark};


    int rnd = new Random().nextInt(color_arr.length);

    linearLayout.setBackgroundResource(color_arr[rnd]); 

Answer 4

For Random Color Generation :

private int getRandomColor() {
  SecureRandom rgen = new SecureRandom();
  return Color.HSVToColor(150, new float[]{
      rgen.nextInt(359), 1, 1
  });
}

And set BackGroundColor of each item after retrieving the item position:

holder.textView.setBackGroundColor(getRandomColor());

Answer 5

Tips: Use modulo operator, to Color each row with 4 colors

export const moduloColor = (rowIndex: number): string => {
let rep
    if (rowIndex % 4 === 0) { // if rowIndex is a multiple of 4
        rep = '#00838F'
    } else if (rowIndex % 3 === 0) { // if rowIndex is a multiple of 3
        rep = '#00ACC1'
    } else if (rowIndex % 2 === 0) { // if rowIndex is a multiple of 2
        rep = '#26C6DA'
    } else {
        rep = '#80DEEA'
    }
return rep
}

modulojavascript