android – 按项目位置在GridView中设置背景

我想在GridView中更改特定项目的背景颜色(按位置).

gridview.getChildAt(1).setBACkgroundresource(android.R.drawable.btn_default);

不起作用.

如果我在OnClickListener中使用它,它的工作原理：

public void onItemClick(AdapterView<?> parent,View view,int position,long id) {
    view.setBACkgroundresource(android.R.drawable.btn_default);
}

但我想在没有点击的情况下改变它.

编辑

ImageAdapter：

public class ImageAdapter extends BaseAdapter {
private final String TAG = getClass().toString();

private Context mContext;

public ImageAdapter(Context C) {
    mContext = c;
}

public int getCount() {
    return mThumbIds.length;
}

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

public long getItemId(int position) {
    return 0;
}

public View getView(int position,View convertView,ViewGroup parent) {
    ImageView imageView;
    if (convertView == null) {  // if it's not recycled,initialize some attributes
        imageView = new ImageView(mContext);
        imageView.setLayoutParams(new GridView.LayoutParams(85,85));
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROp);
        imageView.setPadding(8,8,8);
    } else {
        imageView = (ImageView) convertView;
    }

    parent.getChildAt(1).setBACkgroundColor(Color.RED);

    imageView.setImageresource(mThumbIds[position]);
    return imageView;
}

活动：

final GridView gridview = (GridView) view.findViewById(R.id.gridView);
gridview.setAdapter(new ImageAdapter(MainActivity.this));
gridview.setSELEction(0);
    gridview.setOnItemClickListener(new AdapterView.onItemClickListener() {
    View prevIoUs = null;
    @Override
    public void onItemClick(AdapterView<?> parent,long id) {
            if(prevIoUs == view) {
                view.setBACkgroundresource(android.R.drawable.btn_default);
            } else {
                view.setBACkgroundresource(android.R.drawable.btn_default);
                if(prevIoUs != null) prevIoUs.setBACkgroundresource(0);
                prevIoUs =  view;
            }

        }
    });

XML：

<GridView
    android:id="@+id/gridView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:numcolumns="4" >
</GridView>

gridView.getChildAt(position).setBACkgroundColor(Color.RED);

@Override
public View getView(int position,ViewGroup parent) {

}