Android Listview显示混乱问题

在使用自定义ListView视图时，经常会采用重用ListView中视图的方式来提高滑动和显示效率，但是随之而来的一个问题是listview中数据经常显示混乱。

通常情况下，我们重写的方法是这样的：

inflater = LayoutInflater.from(context);

@Override
  public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder;
    if (convertView == null) {
      convertView = inflater.inflate(R.layout.book_item, null);
      holder = new ViewHolder(convertView);
      Book book = books.get(position);
      holder.bookName.setText(book.getName());
      holder.bookTime.setText(book.getTime());
      convertView.setTag(holder);
    } else {
      holder = (ViewHolder) convertView.getTag();
    }

    return convertView;
  }

  class ViewHolder {
    ImageView bookPic;
    TextView bookName;
    TextView bookTime;

    public ViewHolder(View view) {
      bookPic = (ImageView) view.findViewById(R.id.iv_book_pic);
      bookName = (TextView) view.findViewById(R.id.tv_book_name);
      bookTime = (TextView) view.findViewById(R.id.tv_book_time);
    }
  }

这样通常会造成list显示混乱，是因为当我们重用视图但是convertView != null的时候我们并没有去重新加载数据，写成下面这种形式就会重新加载数据了：

@Override
  public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder;
    if (convertView == null) {
      convertView = inflater.inflate(R.layout.book_item, null);
      holder = new ViewHolder(convertView);
      convertView.setTag(holder);
    } else {
      holder = (ViewHolder) convertView.getTag();
    }
    Book book = books.get(position);//不管视图是否重用，都重新设置数据
    holder.bookName.setText(book.getName());
    holder.bookTime.setText(book.getTime());
    return convertView;
  }