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namespace ProductMaintenance
{
public class Category
{
int _categoryId;
string _name;
string _description;
public int CategoryId
{
get { return _categoryId; }
}
public string Name
{
get { return _name; }
}
public string Description
{
get { return _description; }
}
public Category(int categoryId, string name, string description)
{
_categoryId = categoryId;
_name = name;
_description = description;
}
public override string ToString()
{
return _name;
}
}
}
//这里是给cmbCategoryg下拉框赋值,为什么 "Category item = new Category("这样写呢
using (IDataReader dataReader = _db.ExecuteReader("GetCategories"))
{
// Processing code
while (dataReader.Read())
{
Category item = new Category(
dataReader.GetInt32(0),
dataReader.GetString(1),
dataReader.GetString(2));
this.cmbCategory.Items.Add(item);
}
}
//这是下面的使用(Category)this.cmbCategory.SelectedItem看不懂
Category selectedCategory = (Category)this.cmbCategory.SelectedItem;
这里
Category item = new Category(
dataReader.GetInt32(0),
dataReader.GetString(1),
dataReader.GetString(2));
表示实例化了Category 类,使用Category 类的构造函数为定义的:
public Category(int categoryId, string name, string description)
{
_categoryId = categoryId;
_name = name;
_description = description;
}
//这是下面的使用(Category)this.cmbCategory.SelectedItem看不懂
Category selectedCategory = (Category)this.cmbCategory.SelectedItem;
这里是因为
using (IDataReader dataReader = _db.ExecuteReader("GetCategories"))
{
// Processing code
while (dataReader.Read())
{
Category item = new Category(
dataReader.GetInt32(0),
dataReader.GetString(1),
dataReader.GetString(2));
this.cmbCategory.Items.Add(item);
}
}
this.cmbCategory.Items添加的每一项即为一个Category对象,所以可以使用
(Category)this.cmbCategory.SelectedItem;
进行强类型转换