Question

概述：我现在尝试制作的程序包含以下步骤。

从用户处获取输入数据并将其存储在SQLite数据库中。
使用从数据库中检索的数据填写列表视图。

为了实现1，我首先创建了addNewItem()方法，如下所示。

public void addNewPost(Post post) {
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();

    // get the variables which are to be put into the database row.
    String uploader = post.getUploader();
    String content = post.getContent();
    String privacy_level = post.getPrivacyLevel();
    String uploaded_at = post.getUploadedAt();
    String edited_at = post.getEditedAt();

    values.put(KEY_UPLOADER, uploader);
    values.put(KEY_CONTENT, content);
    values.put(KEY_PRIVACY_LEVEL, privacy_level);
    values.put(KEY_UPLOADED_AT, uploaded_at);
    values.put(KEY_EDITED_AT, edited_at);

    db.insert(TABLE_POST, null, values);
    db.close();
}

对于2，我创建了另一个名为initListView()的方法。

private void initListView() {
    SQLiteDatabase db = sqliteHandler.getWritableDatabase();
    Cursor cursor = db.rawQuery("SELECT * FROM " + SQLiteHandler.TABLE_POST, null);
    username.clear();
    uploaded_at.clear();
    content.clear();

    if(cursor.moveToFirst()) {
        do {
            username.add(cursor.getString(cursor.getColumnIndex(DataKeyLists.KEY_UPLOADER)));
            uploaded_at.add(cursor.getString(cursor.getColumnIndex(DataKeyLists.KEY_UPLOADED_AT)));
            content.add(cursor.getString(cursor.getColumnIndex(DataKeyLists.KEY_CONTENT)));
        } while(cursor.moveToNext());
    }

    FeedAdapter adapter = new FeedAdapter(this, username, uploaded_at, content);
    listView.setAdapter(adapter);
    cursor.close();
}

最后这是FeedAdapter类。

public class FeedAdapter extends BaseAdapter {

    private Context context;
    private ArrayList<String> username;
    private ArrayList<String> uploaded_at;
    private ArrayList<String> content;

    public FeedAdapter(Context context, ArrayList<String> username, ArrayList<String> uploaded_at, ArrayList<String> content) {
        this.context = context;
        this.username = username;
        this.uploaded_at = uploaded_at;
        this.content = content;
    }

    public int getCount() {
        return username.size();
    }

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

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

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

        if(convertView == null) {
            inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.feed_item, null);


            ImageView ivFeedThumbnail = (ImageView) convertView.findViewById(R.id.ivFeedThumbnail);
            TextView tvFeedUsername = (TextView) convertView.findViewById(R.id.tvFeedUsername);
            TextView tvFeedUploaded = (TextView) convertView.findViewById(R.id.tvFeedCreated);
            TextView tvFeedText = (TextView) convertView.findViewById(R.id.tvFeedText);
            TextView tvFeedLikes = (TextView) convertView.findViewById(R.id.tvFeedLikes);
            TextView tvFeedComments = (TextView) convertView.findViewById(R.id.tvFeedComments);
            Button btnLike = (Button) convertView.findViewById(R.id.btnLike);
            Button btnComment = (Button) convertView.findViewById(R.id.btnComment);

            tvFeedUsername.setText(username.get(position));
            tvFeedUploaded.setText(uploaded_at.get(position));
            tvFeedText.setText(content.get(position));

        }

        return convertView;
    }
}

代码似乎没有问题，但是当我运行应用程序时，列表仍然是空的。

非常感谢解决方案的任何提示。

Android：使用sqlite中的数据填充列表视图

0 个答案: