Android - Programming Style - RecyclerView - Use SetText in ViewHolder or in onBindViewHolder?

Question

When setting OnClickListeners to items in the RecyclerView it's recommended to do that in the inner class like this:

public ViewHolder(View itemView) {
    super(itemVIew);
    nameTextView = (TextView) itemView.findViewById(R.id.item_name);
    itemView.setOnClickListener(this);
}

When I see code for setting text it's usually in the onBindViewHolder method:

@Override
public void onBindViewHolder(SetPlayerNameViewHolder holder, int position) {
    holder.nameTextView.setText(String.valueOf("Random Text"));
}

If the text never changes, shouldn't it be in the inner class?

public ViewHolder(View itemView) {
    super(itemVIew);
    nameTextView = (TextView) itemView.findViewById(R.id.item_name);
    nameTextView.setText(String.valueOf("Random Text"));
    itemView.setOnClickListener(this);
}

Edit: And what if you retrieve a value that is different for all TextViews, but should not be updated when the RecyclerView reloads it

public ViewHolder(View itemView) {
    super(itemVIew);
    nameTextView = (TextView) itemView.findViewById(R.id.item_name);

    // Not the actual methods, but to make it more readable
    int i = itemView.getPosition()
    String randomText = getTextFromDatabaseWhereRowIs(i)

    nameTextView.setText(String.valueOf(randomText));
    itemView.setOnClickListener(this);
}

Ferdous Ahamed · Accepted Answer · 2017-04-22T14:47:42.287

Yes you are right...

1. onBindViewHolder(..., int position) get called for individual items of RecyclerView. If your text is different for each item then you should use it from onBindViewHolder() using position to get the correct text.

@Override
public void onBindViewHolder(SetPlayerNameViewHolder holder, int position) {
    String item = YourList.get(position); // For example YourList is an ArrayList of String
    holder.nameTextView.setText(item);
}

2. If text is fixed for each item then you can set it from ViewHolder as you said or you can make it fix from TextView XML using android:text="YOUR_TEXT".

public ViewHolder(View itemView) {
    super(itemVIew);
    nameTextView = (TextView) itemView.findViewById(R.id.item_name);
    nameTextView.setText("Random Text");
}

Hope this will help~

score 0 · Answer 2 · answered Apr 22 '17 at 14:44

This method internally calls onBindViewHolder(ViewHolder, int) to update the RecyclerView.ViewHolder contents with the item at the given position and also sets up some private fields to be used by RecyclerView.

The ViewHolder you are received from the parameter, comes from the Cache or the RecyclerView.RecycledViewPool.

RecycledViewPool lets you share Views between multiple RecyclerViews. If you want to recycle views across RecyclerViews, create an instance of RecycledViewPool and use setRecycledViewPool(RecycledViewPool). RecyclerView automatically creates a pool for itself if you don't provide one.

So If you are not using the same viewType and the same layout across different RecyclerView where the text of the TextView is different in each RecyclerView, then you are right. But if you are doing so, Then RecyclerView might not call createViewHolder(ViewGroup parent, int viewType) as it might a viewHolder from the RecycledViewPool. In that case you can set the text value in onViewAttachedToWindow(VH holder)

Android - Programming Style - RecyclerView - Use SetText in ViewHolder or in onBindViewHolder?

2 Answers2