java - RecyclerView 中的选定项目在滚动时发生变化

Question

我有一个 RecyclerView，其中每个元素代表一个事件。我想让用户通过单击来选择事件。选择后，事件和报告按钮将被着色:

执行单击之前的 UI:click here .

用户界面执行点击后:click here .

这非常简单并且据称有效；我为每个 ViewHolder 设置了一个 OnClickListener ，它负责为项目着色，当触发时，它会触发拥有 Activity 中名为 onOccurrenceSelected 的另一个事件，它负责更改按钮的状态。

但是，当滚动 RecyclerView 的项目时，其他不相关的项目会被着色，就像它们的 OnClickListener 被触发一样(尽管没有触发)，而当向后滚动时，所选事件会被着色为未选中。当发生这种情况时，不会触发唯一应该为项目着色的事件。

对这种行为有什么解释吗？谢谢!

编辑:以下是适配器中的一些相关代码:

private List<Occurrence> mDataSet;
private Activity activity;

public <OccurrencesActivity extends OnOccurrenceSelectedListener> OccurrencesAdapter(OccurrencesActivity occurrencesActivity, List<Occurrence> occurrences) {
    this.activity = (android.app.Activity) occurrencesActivity;
    mDataSet = occurrences;
}

@Override
public void onBindViewHolder(final ViewHolder holder, final int position) {
    Occurrence instance = mDataSet.get(position);
    ...
    setOnClickListener(holder, instance);
    }

private void setOnClickListener(final ViewHolder holder, final Occurrence occurrence) {
    holder.itemView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            if (!occurrence.isSelected()) {
                holder.itemView.setBackgroundColor(App.getContext().getResources().getColor(R.color.turquoise));
                holder.titleTextView.setTextColor(App.getContext().getResources().getColor(R.color.white));
                holder.statusTextView.setTextColor(App.getContext().getResources().getColor(R.color.white));
                holder.dateTextView.setTextColor(App.getContext().getResources().getColor(R.color.white));
                holder.timeTextView.setTextColor(App.getContext().getResources().getColor(R.color.white));
            } else {
                holder.itemView.setBackgroundColor(App.getContext().getResources().getColor(R.color.white));
                holder.titleTextView.setTextColor(App.getContext().getResources().getColor(R.color.turquoise));
                holder.statusTextView.setTextColor(App.getContext().getResources().getColor(R.color.grey));
                holder.dateTextView.setTextColor(App.getContext().getResources().getColor(R.color.grey));
                holder.timeTextView.setTextColor(App.getContext().getResources().getColor(R.color.grey));
            }
            occurrence.setSelected(!occurrence.isSelected());

            ((OnOccurrenceSelectedListener)activity).onOccurrenceSelected(mDataSet);
        }
    });
}

Answer 1

Recyclerview 在滚动时总是重复使用 View ，因此您必须将选定的位置存储到临时数组列表中，然后对 onBindViewHolder 进行条件检查，确定该特定位置是否已存在于数组列表中？我更新了你的适配器。找到以下带有注释的更改

    private List<Occurrence> mDataSet;
private Activity activity;

//Added here temporary ArrayList
private ArrayList<String> mSelectedPosition = new ArrayList<String>;

public <OccurrencesActivity extends OnOccurrenceSelectedListener> OccurrencesAdapter(OccurrencesActivity occurrencesActivity, List<Occurrence> occurrences) {
    this.activity = (android.app.Activity) occurrencesActivity;
    mDataSet = occurrences;
}

@Override
public void onBindViewHolder(final ViewHolder holder, final int position) {


    //Set ViewTag
    holder.itemView.setTag(position);

    //Check everyposition during view binding process
    if(mSelectedPosition.contains(String.valueOf(position))){

     holder.itemView.setBackgroundColor(App.getContext().getResources().getColor(R.color.white));
                holder.titleTextView.setTextColor(App.getContext().getResources().getColor(R.color.turquoise));
                holder.statusTextView.setTextColor(App.getContext().getResources().getColor(R.color.grey));
                holder.dateTextView.setTextColor(App.getContext().getResources().getColor(R.color.grey));
                holder.timeTextView.setTextColor(App.getContext().getResources().getColor(R.color.grey));


     }else{
    holder.itemView.setBackgroundColor(App.getContext().getResources().getColor(R.color.white));
                    holder.titleTextView.setTextColor(App.getContext().getResources().getColor(R.color.turquoise));
                    holder.statusTextView.setTextColor(App.getContext().getResources().getColor(R.color.grey));
                    holder.dateTextView.setTextColor(App.getContext().getResources().getColor(R.color.grey));
                    holder.timeTextView.setTextColor(App.getContext().getResources().getColor(R.color.grey));

      }

    Occurrence instance = mDataSet.get(position);
    ...
    setOnClickListener(holder, instance);
    }

private void setOnClickListener(final ViewHolder holder, final Occurrence occurrence) {
    holder.itemView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

       // Get Position
         int position = (int) view.getTag();

            //Remove SelectedPosition if Already there
              if(mSelectedPosition.contains(position))
                  mSelectedPosition.remove(String.valueOf(position));
               else
                  mSelectedPosition.add(String.valueOf(position));

                notifyDataSetChanged();

               //Not sure about this lines 
                occurrence.setSelected(!occurrence.isSelected());

                ((OnOccurrenceSelectedListener)activity).onOccurrenceSelected(mDataSet);
            }
        });
    }