The first you interfac like:
   public interface OnItemClickListener {
    void onItemClick(ContentItem item);
}
After in Adpter:
private final List<ContentItem> items;
private final OnItemClickListener listener;
public ContentAdapter(List<ContentItem> items, OnItemClickListener listener) {
    this.items = items;
    this.listener = listener;
}
And implement it:
public class ContentAdapter extends RecyclerView.Adapter<ContentAdapter.ViewHolder> {
    public interface OnItemClickListener {
        void onItemClick(ContentItem item);
    }
    private final List<ContentItem> items;
    private final OnItemClickListener listener;
    public ContentAdapter(List<ContentItem> items, OnItemClickListener listener) {
        this.items = items;
        this.listener = listener;
    }
    @Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.view_item, parent, false);
        return new ViewHolder(v);
    }
    @Override public void onBindViewHolder(ViewHolder holder, int position) {
        holder.bind(items.get(position), listener);
    }
    @Override public int getItemCount() {
        return items.size();
    }
    static class ViewHolder extends RecyclerView.ViewHolder {
        private TextView name;
        private ImageView image;
        public ViewHolder(View itemView) {
            super(itemView);
            name = (TextView) itemView.findViewById(R.id.name);
            image = (ImageView) itemView.findViewById(R.id.image);
        }
        public void bind(final ContentItem item, final OnItemClickListener listener) {
            name.setText(item.name);
            Picasso.with(itemView.getContext()).load(item.imageUrl).into(image);
            itemView.setOnClickListener(new View.OnClickListener() {
                @Override public void onClick(View v) {
                    listener.onItemClick(item);
                }
            });
        }
    }
}
In Activity or Fragment:
recycler.setAdapter(new ContentAdapter(items, new ContentAdapter.OnItemClickListener() {
    @Override public void onItemClick(ContentItem item) {
        Toast.makeText(getContext(), "Item Clicked", Toast.LENGTH_LONG).show();
        Intent intent=new Intent(SomeActivity.this, Todo_saveActivity.class);
            startActivityForResult(intent,Request_Code);
    }
}));