Question

C#程序问题:未处理 System.NullReferenceException Message未将对象引用设置到对象的实例

using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
public partial class FrmShow : Form
{
public SE[] engineers = new SE[3];
public FrmShow()
{
InitializeComponent();
}
private void BindLV() //绑定ListView控件
{
lVAssess.Items.Clear();

engineers[0].ID = "段长权";
engineers[0].Name = "段长权";
engineers[0].Age = "段长权";
engineers[0].Score = "段长权";
engineers[0].Assess = "段长权";
engineers[1].ID = "段长权";
engineers[1].Name = "段长权";
engineers[1].Age = "段长权";
engineers[1].Score= "段长权";
engineers[1].Assess= "段长权";
engineers[2].ID = "段长权";
engineers[2].Name = "段长权";
engineers[2].Age = "段长权";
engineers[2].Score = "段长权";
engineers[2].Assess= "段长权";

for (int i = 0; i < engineers.Length; i++)
{
ListViewItem item = new ListViewItem();
item.Text = engineers[i].ID;
item.SubItems.Add(engineers[i].Name = "段长权");
item.SubItems.Add(engineers[i].Age = "18");
item.SubItems.Add(engineers[i].Score = "100");
item.SubItems.Add(engineers[i].Assess = "很好");
lVAssess.Items.Add(item);
}
}

这是一个WindowsForm窗体应用程序，使用数组的方式循环往ListView控件里面添加数据
谁知道哪儿有问题？

Answer 1

engineers[0].ID = "段长权";
这里的engineers[0]并没有初期化，因此直接访问它的属性会抛空指针异常。

起码应该这样初始化一下：

engineers[0] = new SE();
engineers[0].ID = "段长权";

Answer 2

public SE[] engineers = new SE[3];
你只实例化了一个数组，但是数组里面的内容都是为null，
所以在 engineers[0].ID = "段长权";这里就会报空引用的错误。

public SE[] engineers = new SE[3];
for(int intX = 0; intX < engineers.length; intX++)
{
engineers[intX] = new se();
}
这样就可以了。

Answer 3

空引用，有变量为空，但仍然访问了它的属性或者方法，和楼上的意见一样