System.Drawing.Point.ToString C# (CSharp) Method

        public override string ToString() => "{X=" + X.ToString() + ",Y=" + Y.ToString() + "}";

 public void AddPoint(Point pt)
 {
     if(this.point_dict.ContainsKey(pt.ToString()))
     {
         MessageBox.Show("添加坐标失败：\n不能添加已在列表中的坐标！");
         return;
     }
     this.point_dict[pt.ToString()] = pt;
     this.lbxScatterPoints.Items.Add(pt.ToString());
 }