RecyclerView onCreateViewHolder位置背景颜色

Question

I need to set background color inside onCreateViewHolder . So, when my position is equal to position % 2 == 0 then set a background Color, else to set another Color. My background color is standard from all of my rows, that's why i thought to use it inside onCreateViewHolder and not onBindViewHolder . Correct me if i am wrong. The problem is that when i am using holder.getAdapterPosition inside onCreateViewHolder it returns '-1' . It seems normal to me. But how can i fix that?

  @Override
  public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {


    View mView = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.inflate_common_item, viewGroup, false);
    ViewHolder holder= new ViewHolder(mView);
    if(holder.getAdapterPosition % 2 ==0)
    {
       //Row BackgroundColor to red.
    }
    else
    {
      //Row BackgroundColor to Green.
    }
    return holder;

}

So when i use the code above i am getting exception that it is index out of bound. Is there any way to fix ?

Answer 1

Try this:

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
    View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.inflate_common_item, viewGroup, false);
    return new ViewHolder(view);
}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    if(position % 2 ==0) {
        holder.itemView.setBackgroundColor(
                ContextCompat.getColor(holder.itemView.getContext(), R.color.color_red));
    } else {
        holder.itemView.setBackgroundColor(
                ContextCompat.getColor(holder.itemView.getContext(), R.color.color_green)); 
    }
}

Answer 2

According to ideal solution you should write this code in onBindViewHolder to use "getAdapterPosition".

if you want only different background Color of row in onCreateViewHolder than you can try this,This will give you one red color row and one other color row continuously.

you need to create a global variable.

boolean Manual_color = true;

@Override public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {

View mView = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.inflate_common_item, viewGroup, false);
ViewHolder holder= new ViewHolder(mView);
if(Manual_color)
{
   //Row BackgroundColor to red.
   Manual_color = false;
}
else
{
  //Row BackgroundColor to Green.
  Manual_color = true;
}
return holder;

Answer 3

You can set color to the view that you have inflated.

View mView = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.inflate_common_item, viewGroup, false);
ViewHolder holder= new ViewHolder(mView);
if(holder.getAdapterPosition % 2 ==0) {
    mView .setBackgroundColor(ContextCompat.getColor(this, R.color.color_red));
} else {
    mView.setBackgroundColor(ContextCompat.getColor(this, R.color.color_green));
}