android – BaseAdapter选择项目和处理问题
作者：互联网
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];
}
}
解决方法:
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;
}
标签：android-adapter,android,android-listview,baseadapter,inflate 来源： https://codeday.me/bug/20190902/1787610.html