Question

我使用以下代码使用ImageAdapter填充gridview控件。

我希望得到一个gridview项，但int i =（（ViewHolder）imagegrid.getItemAtPosition（0））。imageview.getId（）使应用程序崩溃，为什么？

  protected void onCreate(Bundle savedInstanceState) {
        onCreate(savedInstanceState);
        setContentView(R.layout.photo_main); 
        ImageAdapter imageAdapter = new ImageAdapter();  
        GridView imagegrid = (GridView) findViewById(R.id.PhoneImageGrid);        
        imagegrid.setAdapter(imageAdapter);        
   }



    public class ImageAdapter extends BaseAdapter {
        private LayoutInflater mInflater;

        public ImageAdapter() {
            mInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        }

        public int getCount() {
            return count;
        }

        public Object getItem(int position) {
            return position;
        }

        public long getItemId(int position) {
            return position;
        }        

        public View getView(int position, View convertView, ViewGroup parent) {
            ViewHolder holder;
            if (convertView == null) {
                holder = new ViewHolder();
                convertView = mInflater.inflate(R.layout.photogalleryitem, null);
                holder.imageview = (ImageView) convertView.findViewById(R.id.thumbImage);
                holder.checkbox = (CheckBox) convertView.findViewById(R.id.itemCheckBox);
                convertView.setTag(holder);
            } else {
                holder = (ViewHolder) convertView.getTag();
            }

            holder.checkbox.setId(position);
            holder.imageview.setId(position);           
            holder.imageview.setImageBitmap(thumbnails[position]);
            holder.checkbox.setChecked(thumbnailsselection[position]);
            holder.id = position;            

            return convertView;
        }


    }


    class ViewHolder {
        ImageView imageview;
        CheckBox checkbox;
        int id;
    }

}



<info.dodata.managephoto.PhotoRelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

    <ImageView
        android:id="@+id/thumbImage"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:adjustViewBounds="true"
        android:scaleType="centerCrop" />

    <CheckBox
        android:id="@+id/itemCheckBox"
        android:layout_width="35dp"
        android:layout_height="35dp"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="-2dp"
        android:background="#70f2eada"
        android:text="" />

</info.dodata.managephoto.PhotoRelativeLayout>



package info.dodata.managephoto;
import android.util.AttributeSet;
import android.widget.RelativeLayout;

public class PhotoRelativeLayout extends RelativeLayout {
    public PhotoRelativeLayout(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public PhotoRelativeLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public PhotoRelativeLayout(Context context) {
        super(context);
    }


    @SuppressWarnings("unused")
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        setMeasuredDimension(getDefaultSize(0, widthMeasureSpec), getDefaultSize(0, heightMeasureSpec));

        int childWidthSize = getMeasuredWidth();
        int childHeightSize = getMeasuredHeight();

        heightMeasureSpec = widthMeasureSpec = MeasureSpec.makeMeasureSpec(childWidthSize, MeasureSpec.EXACTLY);
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

}

Answer 1

getItemAtPosition返回一个视图，而不是ViewHolder。你应该有castException，不是吗？

Answer 2

实施项目点击监听器

imagegrid .setOnItemClickListener(new OnItemClickListener() {
   @Override
   public void onItemClick(AdapterView<?> arg0, View arg1, int position, long arg3) {

   }});

基本上，诀窍是通过setTag和getTag方法设置和检索位置索引。 items变量引用包含我的自定义（适配器）对象的数据。

如何通过自定义gridview中的getItemAtPosition获取对象？

2 个答案: