两个窗口，form1和form2.
form1

form2

想实现的功能是在Form2窗口中选择项后，点确定将里面的值在form1窗口的会员信息里的三个textbox里显示出来，但是点击调试程序闪了一下就关闭了，点击开始执行则显示的是未将对象引用设置到对象实例，异常文本为：
System.NullReferenceException: 未将对象引用设置到对象的实例。
   在 WindowsFormsApplication1.Form1.Form1_Load(Object sender, EventArgs e) 位置 D:\WYF\毕业设计（修改）\WindowsFormsApplication1\WindowsFormsApplication1\Form1.cs:行号 22
   在 System.Windows.Forms.Form.OnLoad(EventArgs e)
   在 System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
   在 System.Windows.Forms.Control.CreateControl()
   在 System.Windows.Forms.Control.WmShowWindow(Message& m)
   在 System.Windows.Forms.Control.WndProc(Message& m)
   在 System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   在 System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, I

两个窗口代码为：
form1：
using System;
using System.Collections.Generic;
using
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form2 fv = null;
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            this.textBox1.Text = fv.findv[1].ToString();//这个就是异常文本里指的第22行
            this.textBox3.Text = fv.findv[0].ToString();
            this.textBox3.Text = fv.findv[2].ToString();
        }

        private void toolStripButton1_Click(object sender, EventArgs e)
        {

            Form2 fv = new Form2();
            fv.ShowDialog();
        }

      
    }
}

form2
using System;
using System.Collections.Generic;
using
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace WindowsFormsApplication1
{
    public partial class Form2 : Form
    {

        public string id;
        public string[] findv;


        public Form2()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Sanck.con.Open();
            SqlDataAdapter dap = new SqlDataAdapter("select * from 会员表 where 编号 like '%" + this.textBox1.Text + "%'", Sanck.con);
            DataSet ds = new DataSet();
            dap.Fill(ds);
            dataGridView1.DataSource = ds.Tables[0].DefaultView;
            Sanck.con.Close();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Form1 ss = new Form1();

            using (SqlCommand comd = new SqlCommand("select 编号,姓名,折扣 from 会员表 where 编号='" + id + "'", Sanck.con))
            {
                Sanck.con.Open();
                SqlDataReader dr = comd.ExecuteReader();
                if (dr.HasRows)
                {
                    ss.fv = this;
                    dr.Read();
                    this.findv = new string[3] { dr[0].ToString(), dr[1].ToString(), dr[2].ToString() };
                }
                dr.Close();
                Sanck.con.Close();
            }
            ss.ShowDialog();
            this.Hide();
        }

        private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
        {
            //获取到点击行所属的id
            id = this.dataGridView1.Rows[e.RowIndex].Cells[0].Value.ToString();
        }
    }
}

在Form2的button2_Click方法里面，Form1 ss = new Form1();后面加上一句，ss.fv = this;

[ 本帖最后由 yhlvht 于 2013-4-1 23:48 编辑 ]

if (dr.HasRows)
{
    ss.fv = this;
    dr.Read();
    this.findv = new string[3] { dr[0].ToString(), dr[1].ToString(), dr[2].ToString() };
}
你能把ss.fv = this;这句从if里面拿出来不，因为如果没有进入if，ss.fv就没有被赋值，还是null,在Form1的Load事件里面依然会报错。
不拿出来也行，但在Form1的Load事件里面，你要加个判断，判断fv是不是null，如果是null就不执行后面的语句