Android - 在数据库中获取_id onItemClick

Question

所以我现在有点困惑。我使用的是带有扩展 BaseAdapter 的内部类的 simpleCursorAdapter，这样我就可以在 ListView 中每 x 个项目显示一个广告。现在，当用户单击 ListView 中的某个项目时，会弹出一个对话框，用户可以选择“删除”，这显然会删除该行。在我的数据库适配器中，它需要数据库中的 _id 才能删除行，因此我传递从 onItemClick 方法获得的 ID。现在我了解到，当使用自定义适配器时，onItemClick 中的长 id 返回位置，因此我需要在数据库中查找 _id。

这是我的 onItemClick:

myList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View viewClicked, 
                int position, long idInDB) {

Cursor cursor = (Cursor)parent.getItemAtPosition(position);
                if( cursor != null && cursor.moveToFirst() ){
                    int rowCol = cursor.getColumnIndex("_id");
                    idInDB1 = cursor.getLong(rowCol);

“idInDB1”是从数据库适配器传递给我的删除方法的长整型值。

我像这样设置 SimpleCursorAdapter:

myList.setAdapter(new ListViewAdapter(getActivity(), myCursorAdapter));

这是我必须显示广告的 ListViewAdapter 类:

public class ListViewAdapter extends BaseAdapter {

private Activity mContext;  
private SimpleCursorAdapter listAdapter;  
private LayoutInflater mLayoutInflater;  
private int k = 6; // interval ad every 6 items
int baseItems;
int noAds; // used for listview offset

// Constructor takes in a BaseAdapter 
public ListViewAdapter(FragmentActivity activity, SimpleCursorAdapter delegate) {
    mContext = activity;
    listAdapter = delegate; 
    baseItems = listAdapter.getCount();
    noAds  = baseItems / k;
    mLayoutInflater = (LayoutInflater) mContext  
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

}



@Override
public int getCount() {
    // Total count includes list items and ads.
    return baseItems + noAds;
}

@Override
public Object getItem(int position) {
    // Return null if an item is an ad.  Otherwise return the delegate item.
    if (isItemAnAd(position)) {
        return null;
    }
    return listAdapter.getItem(getOffsetPosition(position));
}

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

@Override
public int getViewTypeCount() {
    return listAdapter.getViewTypeCount() + noAds;
}

@Override
public int getItemViewType(int position) {
    if (isItemAnAd(position)) {
        return listAdapter.getViewTypeCount();
    } else {
        return listAdapter.getItemViewType(getOffsetPosition(position));
    }
}

@Override
public boolean areAllItemsEnabled() {
    return false;
}

@Override
public boolean isEnabled(int position) {
    return (!isItemAnAd(position)) && listAdapter.isEnabled(getOffsetPosition(position));
}

private boolean isItemAnAd(int position) {
    if (position < k) return false;
    // Calculate current offset caused by ads already embedded

    if (position==k){
        return true;
    }
    else {
        return isItemAnAd(position-k);
    }

}




// Get the position that is offset by the insertion of the ads
private int getOffsetPosition(int position) {

    int currentNoAds = position / k;
    return position - currentNoAds;

}



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

    // Display every n list items
    if (isItemAnAd(position)) {
        if (convertView instanceof AdView) {
            // Don’t instantiate new AdView, reuse old one
            return convertView;
        } else {
            // Create a new AdView
            AdView adView = new AdView(mContext);
            adView.setAdSize(AdSize.SMART_BANNER);
            adView.setAdUnitId("ca-app-pub-2454167205089490/6335584363");

            // Disable focus for sub-views of the AdView to avoid problems with
            // trackpad navigation of the list.
            for (int i = 0; i < adView.getChildCount(); i++)
            {
                adView.getChildAt(i).setFocusable(false);
            }
            adView.setFocusable(false);

            // Convert the default layout parameters so that they play nice with
            // ListView.

            float density = mContext.getResources().getDisplayMetrics().density;
            int height = Math.round(AdSize.BANNER.getHeight() * density);
            AbsListView.LayoutParams params = new AbsListView.LayoutParams(
                    AbsListView.LayoutParams.MATCH_PARENT,
                    height);
            adView.setLayoutParams(params);
            AdRequest bannerIntermediateReq = new AdRequest.Builder().build();
            adView.loadAd(bannerIntermediateReq);

            return adView;
        }
    } else {

        // Offload displaying other items to the delegate 
        return listAdapter.getView(getOffsetPosition(position) ,
                convertView, parent);

    }
}
}

我的“idInDB1”始终是 ListView 中顶行的 _id，我似乎不明白为什么。有人吗？

Answer 1

将 onItemClick 中的代码更改为

Cursor cursor = (Cursor)parent.getItemAtPosition(position);
 if( cursor != null && cursor.moveToFirst() ){
     int rowCol = cursor.getColumnIndex("_id");
 idInDB1 = cursor.getLong(rowCol);

至

Cursor cursor = (Cursor)((YourAdapter)listView.getAdapter()).getCursor();
cursor.moveToPosition(positon);
int rowCol = cursor.getColumnIndex("_id");
idInDB1 = cursor.getLong(rowCol);

之所以总是获取第一个id，是因为你将光标移动到第一个位置，然后获取id。