Select items in RecyclerView

Question

Similar question have been asked, but i can\'t get any of them work.

What i want is to select item in RecyclerView, change the background of that item view, and stor

Answer 1

First of all, you asked where to put the onClickListener - you should put it in the onBindViewHolder. You can also attach a onClickListener in the ViewHolder class of your item like so:

public class ViewHolder extends RecyclerView.ViewHolder {
        public ViewHolder(View itemView) {
            super(itemView);
            itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                }
            });
        }
    }

As to implementing a single selection behaviour, the answers given here work but calling onNotifyDatasetChanged is bad for performance if you have a lot of items as it rebinds all views from scratch each time.

The link given by Rafiduzzaman Sonnet is a good tutorial to understand a lot of things about setting up RecyclerView, but I think it makes single selection behaviour complicated. I am going to answer comprehensively giving everything one might need to make it work. Here's how I implemented the single selection behaviour:

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) {
    final YourItemViewHolder itemViewHolder = (YourItemViewHolder) holder;
    //This will remember which one was selected
    itemViewHolder.getItemSelectionIndicator()
            .setSelected(position == mSelectedPosition);
        itemViewHolder.getItemWrapperView()
            .setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Log.d(mLogTag, "Tapped on " + position);
                    //This is the previous selection
                    notifyItemChanged(mSelectedPosition);
                    itemViewHolder.getItemSelectionIndicator().setSelected(true);
                    mSelectedPosition = position;
                    //This is the new selection
                    notifyItemChanged(position);
                }
            });

getItemSelectionIndicator() and getItemWrapperView() are methods inside the item's ViewHolder that return specific views from the item layout. A ItemWrapperView could be the top most Linear/RelativeLayout that wraps the entire item. Setting a click listener on it will ensure clicks work if user taps anywhere in the item's view.

ItemSelectionIndicator can be a Linear or RelativeLayout that has been set a state list drawable background. This means when it is set as selected, it shows a shape drawable automatically to indicate selection. When it is set as unselected, the drawable will be removed automatically. This is what the indicator view looks like:

<RelativeLayout
        android:id="@+id/selection_indicator"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/selection_indicator_state_list"/>

This is selection_indicator_state_list.xml in res/drawable:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <!-- Selected background -->
    <item android:state_selected="true"
          android:drawable="@drawable/item_selection_shape"/>
    <!-- Unselected background -->
    <item android:state_selected="false"
        android:drawable="@color/transparent"/>
</selector>

And this is item_selection_shape.xml in res/drawable:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    //22 is value of transparency, BDBDBD is the color
    <solid android:color="#22BDBDBD"/>
    <stroke android:width="2dp" android:color="@color/md_blue_600"/>
    <corners
        android:radius="3dp"/>
</shape>

Answer 2

Make global variable to store position and handle click listener in ViewHolder. Onclick of item, change the global position value like

textView.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        globalPosition=getAdapterPosition();
        notifyDataSetChanged();
    }
});

then in onBindViewHolder

if(postion==globalPosition)
{
    //change color like
    textview.setTextColor(Color.RED);
}
else
{
    //revert back to regular color 
    textview.setTextColor(Color.WHITE);
}

with this code, the item you clicked get red colored and all other wiil be in white.