Implementing Single Selection in RecyclerView: Solutions and Best Practices

Background and Challenges

In Android development, RecyclerView replaces ListView with more efficient view recycling, but it lacks built-in selection functionality. Developers often need to customize single-selection logic, which involves handling view recycling and state management. In the original code, setting an OnCheckedChangeListener in onBindViewHolder to update the data model did not properly address RecyclerView's view recycling, leading to errors like multiple items being selected or inconsistent states during scrolling.

Core Problem Analysis

The root cause lies in RecyclerView's view recycling mechanism. When users scroll, views that leave the screen may be reused for new positions without resetting old states. The original code set new listeners on each bind without clearing previous states, causing multiple checkboxes to be incorrectly linked. Additionally, calling notifyDataSetChanged during scrolling triggers an IllegalStateException because RecyclerView prohibits data modifications while computing layout or scrolling.

Detailed Solution

Based on the best answer, the key to implementing single selection is maintaining global state to track the last selected item. The following code shows the improved onBindViewHolder method:

public void onBindViewHolder(ViewHolder holder, final int position) {
    holder.mTextView.setText(fonts.get(position).getName());
    holder.checkBox.setChecked(fonts.get(position).isSelected());
    holder.checkBox.setTag(new Integer(position));

    // Set default selection
    if (position == 0 && fonts.get(0).isSelected() && holder.checkBox.isChecked()) {
        lastChecked = holder.checkBox;
        lastCheckedPos = 0;
    }

    holder.checkBox.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            CheckBox cb = (CheckBox) v;
            int clickedPos = ((Integer) cb.getTag()).intValue();

            if (cb.isChecked()) {
                if (lastChecked != null) {
                    lastChecked.setChecked(false);
                    fonts.get(lastCheckedPos).setSelected(false);
                }
                lastChecked = cb;
                lastCheckedPos = clickedPos;
            } else {
                lastChecked = null;
            }
            fonts.get(clickedPos).setSelected(cb.isChecked());
            notifyItemChanged(lastCheckedPos);
            notifyItemChanged(clickedPos);
        }
    });
}

This solution uses static variables lastChecked and lastCheckedPos to record the last selected checkbox and position. By storing position information with setTag, it avoids confusion from view recycling. In the click event, it first deselects the previous item, updates the current one, and refreshes the view locally with notifyItemChanged, improving performance and preventing exceptions.

Performance Optimization and Error Handling

Using notifyItemChanged instead of notifyDataSetChanged is a critical optimization, as it updates only affected items and reduces layout computations. Ensure calls are made outside scrolling states to avoid IllegalStateException. The supplementary answer suggests using RadioButton instead of CheckBox to leverage its native single-selection特性, but adapter design must be considered.

Practical Recommendations

In practice, encapsulate state management within the adapter using SparseBooleanArray or custom model classes for better maintainability. Test with fast scrolling and large datasets to ensure state consistency. Avoid time-consuming operations in onBindViewHolder to maintain smooth scrolling.

Conclusion

By maintaining global state and refreshing views locally, single selection in RecyclerView can be effectively implemented. Developers should deeply understand view recycling mechanisms and choose appropriate UI components and notification methods to build stable and efficient applications.