Android Trick 3: GridView动态加载数据情况下，选中状态的实现

GridView使用AdapterView动态加载数据情况下，无论是在onCreate、Onstart、OnResume方法中调用getChildCount()均为0，这说明数据并没有在Activity最初启动后立即加载为GridView的子View，那如果要把GridView实现为Tab风格的菜单，是必须要调用它的状态选中的，如果在Activity中调用的话就会抛nullpointerexception了，那要怎么操作呢？

 

/** * 构造菜单Adapter * @param menuNameArray 名称 * @param imageResourceArray 图片 * @return FootBarAdapter */ private FootBarAdapter getMenuAdapter(String[] menuNameArray, int[] imageResourceArray) { ArrayList<HashMap<String, Object>> data = new ArrayList<HashMap<String, Object>>(); for (int i = 0; i < menuNameArray.length; i++) { HashMap<String, Object> map = new HashMap<String, Object>(); map.put("itemImage", imageResourceArray[i]); map.put("itemText", menuNameArray[i]); data.add(map); } FootBarAdapter footbarAdapter = new FootBarAdapter(this, data, R.layout.item_menu, new String[] { "itemImage", "itemText" }, new int[] { R.id.item_image, R.id.item_text }); return footbarAdapter; } public class FootBarAdapter extends SimpleAdapter { public FootBarAdapter(Context context, List<? extends Map<String, ?>> data, int resource, String[] from, int[] to) { super(context, data, resource, from, to); } @Override public View getView(int position, View convertView, ViewGroup parent) { View v = super.getView(position, convertView, parent); if (position == TOOLBAR_ITEM_PAGEHOME) { v.setBackgroundResource(R.drawable.bg_toolbar_item_pressed); } return v; } }

 

我们继承了SimplerAdapter，然后Override getView方法，在里边进行选中状态的判断和置背景色为选中色。

 

 

 

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http://blog.youkuaiyun.com/xjanker2/archive/2011/03/22/6267515.aspx