Question

嗨，请任何人帮我解决这个问题.. 我使用listview适配器显示带复选框的图像列表，允许选择多个图像格式列表..代码适用于图像列表不超过屏幕但如果图像超过屏幕（滚动）它会抛出空指针异常。以下是我的代码。

（apterMultiChoice.java）

  public class PhotoAdapterMultiChoice extends BaseAdapter 
  {
public ViewHolder holder;
private Activity activity;
private ArrayList<String> data;
private ArrayList<String> text;
private ArrayList<CheckBox> chkBox;
private static LayoutInflater inflater=null;
public ImageLoader imageLoader; 

    public PhotoAdapterMultiChoice(Activity a, ArrayList<String> title,ArrayList<String>           URL,ArrayList<CheckBox> chkBoxPass) 
{
    activity = (Activity) a;
    data=URL;
    text=title;
    this.chkBox = chkBoxPass;
    inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    imageLoader=new ImageLoader(activity.getApplicationContext());
}
public int getCount() 
{
    return data.size();
}
public boolean getSelect(int position)
{
    return this.chkBox.get(position).isChecked();
}
public int getCountSelect()
{
    return chkBox.size();
}
public Object getItem(int position) 
{
    return this.chkBox.get(position).isChecked();
}
public long getItemId(int position) 
{
    return position;
}
public static class ViewHolder
{
    public TextView text;
    public ImageView image;
    public CheckBox checkBox;
}
public View getView(int position, View convertView, ViewGroup parent) 
{
    System.out.println(this.chkBox.size() +" ---- "+data.size());
    if(this.chkBox.size() < data.size())
    {
        View vi=convertView;
        if(convertView==null)
        {
            System.out.println("convertView is null");
            vi = inflater.inflate(R.layout.photoitemlistmultichoice, null);
            holder=new ViewHolder();
            holder.text=(TextView)vi.findViewById(R.id.text);
            holder.image=(ImageView)vi.findViewById(R.id.image);
            holder.checkBox=(CheckBox) vi.findViewById(R.id.check);
            //this.chkBox.add((CheckBox) vi.findViewById(R.id.check));
            vi.setTag(holder);
        }
        else 
        {
            System.out.println("convertView is Not null");
            this.chkBox.add((CheckBox) vi.findViewById(R.id.check));
            holder=(ViewHolder)vi.getTag();
        }

        System.out.println("Position : "+position);
        holder.text.setText(text.get(position));
        holder.image.setTag(data.get(position));
        //holder.checkBox.setTag(chkBox.get(position));
        //this.chkBox.set(position, chkBox.get(position));
        //this.chkBox.add(holder.checkBox);
        imageLoader.DisplayImage(data.get(position), activity, holder.image,"Photo");
        return vi;
    }
    return null;
}

}

我如何调用适配器

PhotoAdapter adapter = new PhotoAdapter(this, imageNameList, thumbURLList);
listPhoto.setAdapter(adapter); //listPhoto is my listView

（photolist.xml）

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:id="@+id/lblAlbumName"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    />
<ListView
    android:id="@+id/listPhoto"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" 
    android:layout_weight="1"/>
</LinearLayout>

（photoitemlist.xml）

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content">
  <ImageView
      android:id="@+id/image"
      android:layout_width="50dip"
      android:layout_height="50dip" android:src="@drawable/default_photo_icon"  android:scaleType="centerCrop"/>
  <TextView
      android:id="@+id/text"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:layout_weight="1" 
      android:layout_gravity="left|center_vertical" 
      android:textSize="20dip" 
      android:layout_marginLeft="10dip"
      />
</LinearLayout>

请帮助..

感谢...

Answer 1

正如你所说，错误是。当你滚动它时就会出局。因此，您正确地创建了您的观点，但没有正确地回收它们。

this.chkBox.add((CheckBox) vi.findViewById(R.id.check));

看起来是什么导致了您的错误。您不需要再次找到Id，因为您已经有了持有者。

holder.text.setText(text.get(position));
        holder.image.setTag(data.get(position));

您可能希望在其他声明中

带有图像列表的listview不适用于自定义适配器中的多个选择

1 个答案: