Question

我正在尝试突出显示一个GridView元素的背景。

Activity.java：

private CustomAdapter ca;

public void onCreate(Bundle _) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_layout);

    // ...

    GridView gw = (GridView) findViewById(R.id.gridview);
    gw.setAdapter(ca = new CustomAdapter(this));
    gw.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            // attempt 1:
            view.setSelection(true);

            // attempt 2:
            gw.setSelection(position);

            // attempt 3:
            gw.setItemChecked(position, true);

            // tried everything WITH and WITHOUT this:
            ca.notifyDataSetChanged();
        }
    });
}

CustomAdapter.java

public class CustomAdapter extends BaseAdapter {

    private LayoutInflater inflater;

    public CustomAdapter(Context c) {
        inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        // Download items async, and call...
        notifyDataSetChanged();
        // ... in a callback
    }

    // getItem(), getCount() and getItemId() implemented here

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view;
        if( convertView!=null ) view = convertView;
        else {
          view = inflater.inflate(R.layout.grid_item, parent, false);

          // calculate height so that an item is a square
          int height = parent.getHeight();
          if( height>0 ) {
            ViewGroup.LayoutParams params = view.getLayoutParams();
            params.height = height/3;
          }
        }

        ImageView image = (ImageView) view.findViewById(R.id.image);
        image.setImageBitmap( getItemImageBitmap(position) );
        return view;
    }
}

activity_layout.xml

<GridView android:id="@+id/gridview"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:stretchMode="columnWidth"
          android:numColumns="3"


          android:drawSelectorOnTop="false"
          android:choiceMode="singleChoice"
          android:listSelector="@drawable/grid_selector" 

          />
<!-- I've tried any combination of those last three params I could think of -->

grid_item.xml

<?xml version="1.0" encoding="utf-8"?>
<ImageView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/image"
    android:background="@drawable/grid_selector"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"/>

grid_selector.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_selected="true" android:drawable="@android:color/holo_red_dark" />
    <item android:drawable="@android:color/transparent" />
</selector>

我尝试在网格视图中将grid_selector作为项目背景或listSelector属性。

我的目标是在用户点击时突出显示一个项目（之后直到选择其他项目）。

Answer 1

所以我的神奇组合是：

gw.setItemChecked(position, true);

Activity.java 就足够了，

无变更

CustomAdapter.java

listSelector="@drawable/grid_selector" 必须从activity_layout.xml移除，
grid_item.xml必须背景，
在android:state_checked="true"中使用android:state_selected="true" 代替grid_selector.xml。

无法选择GridView项目

1 个答案: