how can i use views from my method in custom adapter?

Question

I was try change textview background color in my custom adapter and i created a method because i want to achieve this method from my activity. So i want to use my views in my method in custom adapter like how we re using holder.txt_product.... in onBindViewHolder() method.

@Override
public void onBindViewHolder(final DeMontageListAdapter.MyViewHolder holder, 
final int position) {

    holder.txt_piston_code.setText(list.get(position).getPistonCode());
}

@Override
public int getItemCount() {
    return list.size();
}

public void changeTextViewBackground(){


}

i want to actieve my views like onBindViewHolder() method at my changeTextViewBackground() method.

Answer 1

You need to implement and set a listener interface for your viewholders to be able to communicate with them through your activity:

Your custom adapter:

     private OnItemClickListener onItemClickListener; //ADD THIS GLOBAL FIELD

     //ADD THIS SETTER
     public void setOnItemClickListener(OnItemClickListener onItemClickListener) 
     {
         this.onItemClickListener = onItemClickListener;
     }

     @Override
     public void onBindViewHolder(final DeMontageListAdapter.MyViewHolder holder, 
     final int position) {

     holder.txt_piston_code.setText(list.get(position).getPistonCode());

     // SET YOUR LISTENER TO EACH OF YOUR ITEM VIEWS
     holder.txt_piston_code.setOnClickListener(v ->
            onItemClickListener.onClickItem(position);
     }

     // ADD THIS INTERFACE AT THE END
     interface OnItemClickListener {
        void onClickItem(int position);
     }

Your activity should implement DemontageListAdapter.OnItemClickListener and Override its onClickItem method:

    public class MyActivity implements DemontageListAdapter.OnItemClickListener {

        DemontageListAdapter adapter;

        { ... }

        adapter = new DemontageListAdapter (...)
        adapter.setOnItemClickListener(this); // ADD THIS BEFORE YOU SET YOUR ADAPTER TO YOUR ACTIVITY
        recyclerView.setAdapter(adapter);

        //OVERRIDE THIS METHOD OF YOUR INTERFACE
        @Override
        public void onClickItem(int position) {
            adapter.changeTextViewBackground(position);
        }
    }