滚动时自动选中/取消选中复选框的 RecyclerView

Question

这是我的QuestionHolder：

 private class QuestionHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

    private JSONObject question;
    private CheckBox checkBox;
    private TextView question_txt;
    public QuestionHolder(final LayoutInflater inflater, ViewGroup parent) {
        super(inflater.inflate(R.layout.question_item, parent, false));

        checkBox  = (CheckBox) itemView.findViewById(R.id.question_checkbox);

        checkBox.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //try {
                    //Toast.makeText(getActivity(), "ID: " + question.get("_id"), Toast.LENGTH_SHORT).show();
                //} catch (JSONException e) { }
                // TODO: If this was checked then add the question's id to the answered list
            }
        });
        question_txt = (TextView) itemView.findViewById(R.id.question);
        itemView.setOnClickListener(this);
    }

这里我绑定questiontxt:

public void bind(JSONObject question) {
  this.question = question;
  try {
    question_txt.setText(question.getString("_question"));
  } catch (JSONException je) { }
}

@Override
public void onClick(View v) {
  // TODO: If this was checked then add the question's id to the answered list
}
}

这是我的适配器，扩展 QuestionHolder:

private class QuestionAdapter extends RecyclerView.Adapter<QuestionHolder> {

    private JSONArray questions;

    public QuestionAdapter(JSONArray questions) {
        this.questions = questions;
    }

    @Override
    public QuestionHolder onCreateViewHolder(ViewGroup parent, int viewType) 
{
        return new QuestionHolder(LayoutInflater.from(getActivity()), parent);
    }

这是onBindViewHolder：

@Override
public void onBindViewHolder(QuestionHolder holder, int position) {
  try {
    final JSONObject question = questions.getJSONObject(position);
    holder.bind(question);
  } catch (JSONException je) { }
}

@Override
public int getItemCount() {
  return questions.length();
}
}

这是QuestionHolder：

private class QuestionHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

    private JSONObject question;
    private CheckBox checkBox;
    private TextView question_txt;
    public QuestionHolder(final LayoutInflater inflater, ViewGroup parent) {
        super(inflater.inflate(R.layout.question_item, parent, false));

        checkBox  = (CheckBox) itemView.findViewById(R.id.question_checkbox);

        checkBox.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //try {
                    //Toast.makeText(getActivity(), "ID: " + question.get("_id"), Toast.LENGTH_SHORT).show();
                //} catch (JSONException e) { }
                // TODO: If this was checked then add the question's id to the answered list
            }
        });
        question_txt = (TextView) itemView.findViewById(R.id.question);
        itemView.setOnClickListener(this);
    }

    public void bind(JSONObject question) {
        this.question = question;
        try {
            question_txt.setText(question.getString("_question"));
        } catch (JSONException je) { }
    }

    @Override
    public void onClick(View v) {
        // TODO: If this was checked then add the question's id to the answered list
    }
}

Answer 1

这是因为您的ViewHolder 在滚动时被回收。因此，您需要为每个项目位置保留 CheckBox 的状态。您可以使用SparseBooleanArray 来处理。

你可以这样做：

private class QuestionAdapter extends RecyclerView.Adapter<QuestionHolder> {

  SparseBooleanArray checkedItems = new SparseBooleanArray();

  ...

  @Override
  public void onBindViewHolder(QuestionHolder holder, int position) {
    try {
      final JSONObject question = questions.getJSONObject(position);

      // Remember to change access modifier of checkBox in your ViewHolder
      // Get the state from checkedItems. If no previous value, it will return false.
      holder.checkBox.setChecked(checkedItems.get(position));

      // This is a sample. Do not use create listener here.
      checkBox.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
          // save the check state
          checkedItems.put(position, true);
        }

      holder.bind(question);
    } catch (JSONException je) { }
  }

  ...

}

Answer 2

RecyclerView 在滚动时从布局中移除（回收）看不见的视图，这是 recyclerView 的基本行为，以减少内存使用。

所以当一个带有复选框的视图被“回收”时，一个 checked 复选框被取消选中，如果它有一个监听器，监听器就会被调用。

当监听器被回收时，你可以从视图中移除它。只需覆盖 onViewRecycled 方法。

 @Override
    public void onViewRecycled(@NonNull MyViewHolder holder) {
        if (holder.checkBox != null) {
            holder.checkBox.setOnClickListener(null);
        }
        super.onViewRecycled(holder);
    }

当视图再次构建时，在滚动的同时，你的监听器也会被再次添加。