Question

我正在创建一个程序，该程序允许用户在6个单独的文本框中键入各种数据，然后将其保存到名为Book的对象中。现在，我已轻松完成此操作，但是现在，我希望能够在列表框中选择Book对象并将数据填充回文本框中，我认为这与将加法转换到一定程度一样容易，但是我已经点击了障碍。

这是我的上下文添加按钮的主要部分（我对其进行了评论，希望可以清除所有变量名）

//use class book to create a new book 
Book addBook = new Book();
//use int.tryparse to convert the txtISBN to an int and store in the book object
bool parsed = int.TryParse(txtISBN.Text, out int isbn);
if (parsed)
{
    addBook.gsISBN = isbn;
}
else
{
    MessageBox.Show("Invalid ISBN, Please enter an integer value");
    return;
}
//use double.tryparse to convert the txtPrice into a double and store in the book object
bool parse = double.TryParse(txtPrice.Text, out double price);
if (parsed)
{
    addBook.gsPrice = price;
}
else
{
    MessageBox.Show("Invalid Price, please enter a double value");
    return;
}
//use object addBook with the various getters and setters for 
//each variable and have them equal their textbox equivalent .
addBook.gsAuthor = txtAuthor.Text;
addBook.gsTitle = txtBookTitle.Text;
addBook.gsPublisher = txtPublisher.Text;
addBook.gsDate = txtDate.Text;
//myBooks( this is the Array)
myBooks[currentIndex] = addBook;

上面这段代码有效，但是下面的代码无效，这是我希望弄清楚的。

private void lstbook_SelectedIndexChanged(object sender, EventArgs e)
{
    if (lstbook.SelectedIndex == -1)//if there is no selected game output error message
    {
        MessageBox.Show("Please select a book");
    }
    else
    {
        int index = lstbook.SelectedIndex;
        Book getBook = new Book();
        myBooks[currentIndex] = getBook;
        txtAuthor.Text = getBook.gsAuthor;
    }
}

Answer 1

是的，这很容易。假设您有书籍数组，将其分配给DataSource

Book[] books = //.... retrieve books here
lstBooks.DisplayMember = "Name"; // Book.Name
lstBooks.ValueMember = "Isbn"; // Book.Isbn, but it is don't matter for our logic
lstBooks.DataSource = books; // in this order, please

现在，请记住，您所有的书都在那里，您可以使用lst.SelectedItem对其进行检索。因此，请在SelectedIndexChanged上执行以下操作：

// clear text boxes here first 
Book selectedBook = lstBooks.SelectedItem as Book;
if (selectedBook != null)
{
    txtIsbn.Text = selectedBook.Isbn;
    txtName.Text = selectedBook.Name;
}
else
    MessageBox.Show("Please select a book");

这也可以使用BindingSource来实现，您可以在其中绑定所有控件，而无需手动填充字段。

对象数组，将数据检索到文本框

1 个答案: