Add a New Member to a Collection Object (.NET)

To add a new member to the collection, use the Add method. For example, the following code creates a new layer and adds it to the Layer table:

VB.NET

Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.DatabaseServices
 
<CommandMethod("AddMyLayer")> _
Public Sub AddMyLayer()
  '' Get the current document and database, and start a transaction
  Dim acDoc As Document = Application.DocumentManager.MdiActiveDocument
  Dim acCurDb As Database = acDoc.Database
 
  Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction()
      '' Returns the layer table for the current database
      Dim acLyrTbl As LayerTable
      acLyrTbl = acTrans.GetObject(acCurDb.LayerTableId, _
                                   OpenMode.ForRead)
 
      '' Check to see if MyLayer exists in the Layer table
      If Not acLyrTbl.Has("MyLayer") Then
          '' Open the Layer Table for write
          acLyrTbl.UpgradeOpen()
 
          '' Create a new layer table record and name the layer "MyLayer"
          Using acLyrTblRec As LayerTableRecord = New LayerTableRecord
              acLyrTblRec.Name = "MyLayer"
 
              '' Add the new layer table record to the layer table and the transaction
              acLyrTbl.Add(acLyrTblRec)
              acTrans.AddNewlyCreatedDBObject(acLyrTblRec, True)
          End Using

          '' Commit the changes
          acTrans.Commit()
      End If
 
      '' Dispose of the transaction
  End Using
End Sub

C#

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
 
[CommandMethod("AddMyLayer")]
public static void AddMyLayer()
{
  // Get the current document and database, and start a transaction
  Document acDoc = Application.DocumentManager.MdiActiveDocument;
  Database acCurDb = acDoc.Database;
 
  using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
  {
      // Returns the layer table for the current database
      LayerTable acLyrTbl;
      acLyrTbl = acTrans.GetObject(acCurDb.LayerTableId,
                                   OpenMode.ForRead) as LayerTable;
 
      // Check to see if MyLayer exists in the Layer table
      if (acLyrTbl.Has("MyLayer") != true)
      {
          // Open the Layer Table for write
          acLyrTbl.UpgradeOpen();
 
          // Create a new layer table record and name the layer "MyLayer"
          using (LayerTableRecord acLyrTblRec = new LayerTableRecord())
          {
              acLyrTblRec.Name = "MyLayer";
 
              // Add the new layer table record to the layer table and the transaction
              acLyrTbl.Add(acLyrTblRec);
              acTrans.AddNewlyCreatedDBObject(acLyrTblRec, true);
          }

          // Commit the changes
          acTrans.Commit();
      }
 
      // Dispose of the transaction
  }
}

VBA/ActiveX Code Reference

Sub AddMyLayer()
    Dim newLayer as AcadLayer
    Set newLayer = ThisDrawing.Layers.Add("MyLayer")
End Sub