按项目位置在 GridView 中设置背景

Question

我想更改 GridView 中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，它会起作用：

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

但我想不点击就改变它。

---

编辑

图像适配器：

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, 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, View view,
                int position, 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>

Answer 1

在您的中使用它getView()并查看您的背景是否发生变化：

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

不要忘记使用@Override：getView()

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

}