android – BaseAdapter选择项目和处理问题

[weixin_38082570]

我有一个扩展BaseAdapter的ListView.我有一个data []数组. ListView正确地膨胀和填充.我想要做的是当用户选择项目时,在列表项目上显示一个ImageView(基本上是膨胀视图右侧的检查图像),如果选择了上一个项目,我只是隐藏了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什么吗？ 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]; } }

[weixin_38098983]

But after I select a new item and scroll back and forth I see wierd behavior, the check image is sometimes visible in multiple list items or is hidden in the actual item that is currently selected. 由于您为convertView设置单击侦听器的方式,这很可能发生.您只为convertView为null时的情况设置OnCLickListener,但是当您向上和向下滚动ListView时,行将被回收,您最终将获得与其他行相同的侦听器. 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,您应该在convertView上删除OnCLickListener,并在ListView元素上使用OnItemClickListener.从这个监听器回调你将修改行： 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; }