Question

我的ListView扩展了BaseAdapter。我有一个data []数组。 ListView正确填充和填充。我想要做的是当用户选择项目并且如果选择了之前的项目时，在列表项目上显示ImageView（基本上是在膨胀的视图右侧的检查图像），我只是隐藏ImageView。这也很好。

但是在我选择一个新项目并来回滚动后，我看到了奇怪的行为，检查图像有时在多个列表项中可见，或隐藏在当前选中的实际项目中。有人可以帮忙解释我做错了吗？

我在onCreate方法中有这两行：

    adap = new EfficientAdapter(this);
    lstview.setAdapter(adap);

和适配器代码：

public static class EfficientAdapter extends BaseAdapter implements Filterable {
  private LayoutInflater mInflater;
  private Context context;
  private ImageView CurrentSelectedImageView;
  private Integer CurrentPosition = 14;


  public EfficientAdapter(Context context) {
    mInflater = LayoutInflater.from(context);
    this.context = context;
  }


  public View getView(final int position, View convertView, ViewGroup parent) {

    ViewHolder holder;

    //Log.e("TAG",String.valueOf(position));

    if (convertView == null) {
      convertView = mInflater.inflate(R.layout.adaptor_content, null);

      holder = new ViewHolder();
      holder.textLine = (TextView) convertView.findViewById(R.id.txtCategoryCaption);
      holder.iconLine = (ImageView) convertView.findViewById(R.id.iconLine);
      holder.imgCheckbox = (ImageView) convertView.findViewById(R.id.imgCheck);


      //If the CurrentPosition == position then make the checkbox visible else dont.
      if (CurrentPosition == position){

        holder.imgCheckbox.setVisibility(View.VISIBLE);
      }else{
        holder.imgCheckbox.setVisibility(View.INVISIBLE);
      }


      final ImageView Checkbox = holder.imgCheckbox;

      //Now if the list item is clicked then set the position as the current item and make the checkbox visible.

      convertView.setOnClickListener(new OnClickListener() {
        private int pos = position;

        @Override
        public void onClick(View v) {
            if (CurrentSelectedImageView!=null){
                CurrentSelectedImageView.setVisibility(View.INVISIBLE);
            }
            Checkbox.setVisibility(View.VISIBLE);
            CurrentSelectedImageView = Checkbox;
            CurrentPosition = pos;

        }
      });

      convertView.setTag(holder);
    } else {
      holder = (ViewHolder) convertView.getTag();
    }


        int id = context.getResources().getIdentifier("nodeinsert", "drawable", context.getString(R.string.package_str));
        if (id != 0x0) {
          mIcon1 = BitmapFactory.decodeResource(context.getResources(), id);
        }

        holder.iconLine.setImageBitmap(mIcon1);
        holder.textLine.setText(String.valueOf(data[position]));


    if (CurrentPosition == position){
        Log.e("TAG",CurrentPosition + "---" + String.valueOf(position));
        holder.imgCheckbox.setVisibility(View.VISIBLE);
    }else{
        holder.imgCheckbox.setVisibility(View.INVISIBLE);
    }


    return convertView;
  }



  static class ViewHolder {
    TextView textLine;
    ImageView iconLine;
    ImageView imgCheckbox;
  }

  @Override
  public Filter getFilter() {
    // TODO Auto-generated method stub
    return null;
  }

  @Override
  public long getItemId(int position) {
    // TODO Auto-generated method stub
    return 0;
  }

  @Override
  public int getCount() {
    // TODO Auto-generated method stub
    return data.length;
  }

  @Override
  public Object getItem(int position) {
    // TODO Auto-generated method stub
    return data[position];
  }

}

Answer 1

但是在我选择一个新项目并来回滚动后，我看到了很奇怪行为，检查图像有时在多个列表项中可见或者隐藏在当前选中的实际项目中。

由于您为convertView设置点击监听器的方式，最有可能发生这种情况。您仅在OnCLickListener为convertView的情况下设置了null，但当您向上和向下滚动ListView时，行将被回收，您最终会得到相同的结果监听器作为其他行。

无论如何，如果你只想让一行显示图像，那么有一种更简单的方法。首先，您应该将OnCLickListener放在convertView上，并使用OnItemClickListener元素上的ListView。从此侦听器回调中，您将修改行：

lstview.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> l, View v, int position,
                    long id) {
                View oldView = l.getChildAt(adap.getSelectedPosition());
                ImageView img;
                if (oldView != null && adap.getSelectedPosition() != -1) {
                    img = (ImageView) oldView.findViewById(R.id.imageView1);
                    img.setVisibility(View.INVISIBLE);
                }
                img = (ImageView) v.findViewById(R.id.imageView1);
                img.setVisibility(View.VISIBLE);
                adap.setSelectedPosition(position);
            }
        });

然后像这样修改适配器：

// a field in the adapter
private int mSelectedPosition = -1;

// getter and setter methods for the field above
public void setSelectedPosition(int selectedPosition) {
    mSelectedPosition = selectedPosition;
    notifyDataSetChanged();
}

public int getSelectedPosition() {
    return mSelectedPosition;
}

// and finally your getView() method
public View getView(final int position, View convertView, ViewGroup parent) {
    ViewHolder holder;
    if (convertView == null) {
      convertView = mInflater.inflate(R.layout.adaptor_content, parent, false);
      holder = new ViewHolder();
      holder.textLine = (TextView) convertView.findViewById(R.id.txtCategoryCaption);
      holder.iconLine = (ImageView) convertView.findViewById(R.id.iconLine);
      holder.imgCheckbox = (ImageView) convertView.findViewById(R.id.imgCheck);
      convertView.setTag(holder);
    } else {
      holder = (ViewHolder) convertView.getTag();
    }
    if (mSelectedPosition == position) {
    holder.imgCheckbox.setVisibility(View.VISIBLE);
    } else {
    holder.imgCheckbox.setVisibility(View.INVISIBLE);
    }     
      // what is the point of this call?!
      // you should move this to another place(like the adapter's constructor), the getIdentifier()
      // method is a bit slow and you call it each time the adapter calls getView()
      // you should never use it in the getView() method(), especially as all you do is get the id of the same drawable again and again
      int id = context.getResources().getIdentifier("nodeinsert", "drawable", context.getString(R.string.package_str));
      // ?!?
      if (id != 0x0) {
          mIcon1 = BitmapFactory.decodeResource(context.getResources(), id);
      }
      holder.iconLine.setImageBitmap(mIcon1);
      holder.textLine.setText(String.valueOf(data[position]));
      return convertView;
}

BaseAdapter选择项目和处理问题

1 个答案: