如何在RecyclerVIew上实现项目计数器？

Question

I want to implement Item counter on RecyclerView in android. If we scroll the list so item counter will increase like below Image. I am new in android so Please suggest me what is it called and where can we get it to read it. Thanku

Answer 1

if you are using Array Adapter, you can set your counter text with item position overriding getView method in your adapter:

@Override
    public View getView(int position, View convertView, ViewGroup parent) {
        //necessary code for inflating list items
        //as index position starts from 0, set position+1 in textview
        tvCounter.setText(Integer.parseInt(position+1)); 
        return convertView;
    }

if you are using RecyclerView Adapter , you can set your counter text with item position overriding onBindViewHolder method in your adapter:

@Override
    public void onBindViewHolder(ItemViewHolder holder, int position) {
        //other parts

        //as index position starts from 0, set position+1 in textview
        holder.tvCounter.setText(Integer.toString(position+1));
    }

Answer 2

findFirstVisibleItemPosition() will return visible item position while scroll top/bottom.

LinearLayoutManager myLayoutManager = myRecyclerView.getLayoutManager();
int scrollPosition = myLayoutManager.findFirstVisibleItemPosition();

for more about read this.

Answer 3

Create BroadcastReceiver in your activity/fragment.

private BroadcastReceiver counterChangeReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        //set text by getting value from intent extras
    }
};

and register it in activity/fragment onResume() like this

LocalBroadcastManager.getInstance(context).registerReceiver(counterChangeReceiver , new IntentFilter("COUNTER_CHANGE"));

Send broadcast from onBindViewHolder() something like this

 Intent intent = new Intent("COUNTER_CHANGE");
 intent.putExtra("value",(position+1));
 LocalBroadcastManager.getInstance(MyApplication.getInstance().getBaseContext()).sendBroadcast(intent);