在android的listview中删除选定的行

Question

我有一个带有自定义行的列表视图，其中包含一个文本视图和一个用于删除该行的可点击图像。 Listview 从 sqlite 数据库中获取数据。我已成功将数据库中的数据加载到列表视图中。我想要的是在按下删除按钮时从数据库中删除该行。我知道这需要将 onclick 事件处理程序绑定到删除按钮并获取与行绑定的对象或 sqlite 数据。如何获取与用户单击删除按钮的行绑定的 sqlite 数据？ 这是我的列表视图适配器

public class CommentAdapter extends ArrayAdapter<Comment> {

// private objects
private List<Comment> mListComment;
private LayoutInflater mInflater;

public CommentAdapter(Context c,int textViewResourceId, List<Comment> list) {
    super(c, textViewResourceId, list);
    mListComment = list;
    // create layout inflater
    mInflater = LayoutInflater.from(c);
}

@Override
public int getCount() {
    return mListComment.size();
}

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

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    // get view reference
    View view = convertView;
    // if null
    if(view == null) {
        // inflate new layout
        view = mInflater.inflate(R.layout.comment_row, null);
        // create a holder
        ViewHolder holder = new ViewHolder();
        // find controls
        holder.txtComment = (TextView)view.findViewById(R.id.txtComment);
        holder.btnDelete = (ImageView)view.findViewById(R.id.btnDelete);
        // set data structure to view
        view.setTag(holder);
    }

    Comment cmt = mListComment.get(position);
    // if not null
    if(cmt != null) {
        // query data structure
        ViewHolder holder = (ViewHolder)view.getTag();
        // set data to display
        holder.txtComment.setText(cmt.getComment());
        holder.btnDelete.setClickable(true);
        holder.btnDelete.setImageResource(android.R.drawable.ic_delete);

    }

    // return view
    return view;
}

/*
 * @class ViewHolder
 * to hold data structure on view with comment info
 */
static class ViewHolder {
    private TextView txtComment;
    private ImageView btnDelete;

}
}

这是我的 CommentsDataSource 类

public class CommentsDataSource {
private SQLiteDatabase database;
private DatabaseHelper dbHelper;
private String[] allColumns = { DatabaseHelper.COLUMN_ID, DatabaseHelper.COLUMN_COMMENT };

public CommentsDataSource(Context context) {
    dbHelper = new DatabaseHelper(context);
}

public void open() throws SQLException {
    database = dbHelper.getWritableDatabase();
}

public void close() {
    dbHelper.close();
}

public Comment createComment(String comment) {
    //insert into databasae
    return newComment;
}

private Comment cursorToComment(Cursor cursor) {
    //convert cursor to comment
    return comment;
}

public void deleteComment(Comment comment) {
    //delete row from datbase
}


public List<Comment> getAllComments() {
    //get all rows
    return comments;
}

}

Answer 1

将您的 getView 方法移动如下：

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    // get view reference
    View view = convertView;
    // if null
    if(view == null) {
        // inflate new layout
        view = mInflater.inflate(R.layout.comment_row, null);
        // create a holder
        ViewHolder holder = new ViewHolder();
        // find controls
        holder.txtComment = (TextView)view.findViewById(R.id.txtComment);
        holder.btnDelete = (ImageView)view.findViewById(R.id.btnDelete);
        // set data structure to view
        view.setTag(holder);
    }

    final Comment cmt = mListComment.get(position);
    // if not null
    if(cmt != null) {
        // query data structure
        ViewHolder holder = (ViewHolder)view.getTag();
        // set data to display
        holder.txtComment.setText(cmt.getComment());
        holder.btnDelete.setClickable(true);
        holder.btnDelete.setImageResource(android.R.drawable.ic_delete);
        holder.btnDelete.setOnClickListener(new View.OnClickListener(){
               public void onClick(View view)
               {
                     commentsDataSource.deleteComment(cmt);
                     //Requery DB to get Updated results
                     notifyDataSetChanged();
               }
        })

    }

    // return view
    return view;
}

Answer 2

您需要在扩展的ListActivity 中设置您的onlistitemclicklistener。应该是这样的。

@Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        ViewHolder item = (ViewHolder ) getListAdapter().getItem(position);
        Toast.makeText(this, item.txtComment  + " selected", Toast.LENGTH_LONG).show();
    }

现在，让您的处理程序删除选定的行。你有listview、current view 和indexed id。希望，它会工作

Answer 3

为按钮单击编写一个监听器，并在 onClick() 方法中使用以下代码：

@Override
protected void onClick(View view){
    view.getParent().setVisibility(View.GONE);
}

我希望这对你有用。 或者，由于我没有时间检查上面的代码，如果这不起作用，在getView()方法中，您可以将view和按钮存储到两个单独的ArrayList中，然后获取索引onClick() 中的按钮，来自按钮ArrayList，并将视图ArrayList 中相同索引的可见性设置为GONE。这种方法有点脏，所以我更喜欢上面的方法。

Answer 4

Listview.setOnItemClickListener(new OnItemClickListener() { 
    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1, int position, long arg3) {
        // TODO Auto-generated method stub
        List.remove(position);   
        notifyDataSetChanged();
    }
});