未将对象引用设置到对象的实例

对象引用没有设置到对象实例的原因很多：

1、如下：

  public int Revise(ref int numline, ref int numcircle, ref int numtext,System.IO.StreamWriter str_w, List< string > record,EXT extend,Line [] lines, Circle[] circles, Text [] texts)

        {

            string [] record1 =record.ToArray();

            for (int i = 0; i < record1.Length;i++ )

            {

                string temp = string .Empty;

                temp = record1[i];

                if (temp == "$EXTMIN" )

                {

                    record1[i + 2] = Convert .ToString(extend.Min_x) ;

                    record1[i + 4] = Convert .ToString(extend.Min_y);

                    record1[i + 6] = Convert .ToString(extend.min_z);

                    record1[i + 10] = Convert .ToString(extend.Max_x);

                    record1[i + 12] = Convert .ToString(extend.Max_y);

                    record1[i + 14] = Convert .ToString(extend.Max_z);

                    i += 14;

                    continue ;

                }

                if (temp == "AcDbLine" )

                {

                    record1[i + 2]= Convert .ToString(lines[numline].x1);//此处开始报错

                    record1[i + 4] = Convert .ToString(lines[numline].y1);

                    record1[i + 6] = Convert .ToString(lines[numline].z1);

                    record1[i + 8] = Convert .ToString(lines[numline].x2);

                    record1[i + 10] = Convert .ToString(lines[numline].y2) ;

                    record1[i + 12] = Convert .ToString(lines[numline].z2);

                    numline--;

                    i += 12;

                    continue ;

                }

            }

            for (int i = 0; i < record1.Length;i++ )

            {

                str_w.WriteLine(record1[i]);

            }

            return 1;

        }

其中numline,numcircle,numtext，代表的line，circle，text对象的个数

原因就在于，数组的下标总是比个数小1，假如有5个元素，我们尝试给lines[5]赋值，而lines[5]已经越界，更不可能初始化。

2、对于数组，不光要实例化数组，还要实例化数组的对象

  public int Read_Entities(ref   int numpolyline, Polyline [] plines,System.IO. StreamReader str_r)

        {

            string buff = string .Empty;

            buff = str_r.ReadLine();

            //int numline = 0;

            //int numcircle = 0;

            //int numtext=0;

            while (buff != "OBJECTS" )

            {

              

                if (buff == "LWPOLYLINE" )

                {

                    while (buff != "AcDbPolyline" )

                    {

                        buff = str_r.ReadLine();

                    }

                    plines[numpolyline] = new Polyline ();//(1)

                    str_r.ReadLine();

                    plines[numpolyline].pointnum = Convert .ToInt32(str_r.ReadLine());

                    str_r.ReadLine();

                    str_r.ReadLine();

                    str_r.ReadLine();

                    str_r.ReadLine();

                    plines[numpolyline].points = new point [plines[numpolyline].pointnum];//(2)

                    for (int i=0;i<plines[numpolyline].pointnum;i++)

                    {

                        plines[numpolyline].points[i] = new point ();//(3)

                        str_r.ReadLine();

                        plines[numpolyline].points[i].x = Convert .ToDouble(str_r.ReadLine());

                        str_r.ReadLine();

                        plines[numpolyline].points[i].y = Convert .ToDouble(str_r.ReadLine());

                    }

                }

                buff = str_r.ReadLine();

            }

            return 1;

        }

其中，多线由多个点组成

注释（1）处：初始化polyline对象

注释（2）处：初试化point数组

注释（3）处：初始化点对象实例

一直忘记了第二个，导致一直提示错误

待续。。。