Error System.NullReferenceException in code - HELP!!!

Anonymous — Wed, 08 Jun 2005 13:30:14 GMT

What is wrong with this code, i allways get this error:
"System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NullReferenceException: Object reference not set to an instance of an object.
at RSNNAcadApp.ExtendedCommands.Distance.DistanceOnCurve()"

[code]#region Using directives

using System;
//using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.Globalization;

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;

using System.Runtime.InteropServices;

#endregion

namespace RSNNAcadApp.ExtendedCommands
{
public class Distance
{
//this is an undocumented api exported from acad.exe. Use it at your own risk.
//
// Setting this flag tells AutoCAD to display the last string output to the command line
//in the Dynamic Input prompt window (one time only.)
[DllImport("acad.exe", EntryPoint = "?acedSetDynInputDisplayMessage@@YA_N_N@Z")]
private static extern bool acedSetDynInputDisplayMessage(bool displayMessageOnce);

private int Luprec = Application.DocumentManager.MdiActiveDocument.Database.Luprec;

private Curve CurveObj;
private Point3d FirstPoint;
private Point3d SecondPoint;

private double DistFP;
private double DistSP;
private double Dist;
private string DistFPPrompt;
private string DistSPPrompt;
private string DistPrompt;

public Distance()
{
}

[CommandMethod("AbstandKurve", CommandFlags.Modal)]
public void DistanceOnCurve()
{

Database db = HostApplicationServices.WorkingDatabase;
Transaction myT = db.TransactionManager.StartTransaction();
Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
try
{
PromptEntityOptions entopts = new PromptEntityOptions("Objekt zeigen");
entopts.Message = "Objekt zeigen";
PromptEntityResult ent = null;
bool RightObject = false;

while (!RightObject)
{
while (ent.Status == PromptStatus.Error)
{
ent = ed.GetEntity(entopts);
}

if (ent.Status == PromptStatus.Cancel)
return;

if (ent.Status == PromptStatus.OK)
{
ObjectId entid1 = ent.ObjectId;
Entity tmpEnt = (Entity)myT.GetObject(entid1, OpenMode.ForRead);
CurveObj = tmpEnt as Curve;
if (CurveObj != null)
{
RightObject = true;

//highlight the entity
ObjectId[] ids = new ObjectId[1];
ids[0] = entid1;

SubentityId index = new SubentityId(SubentityType.Edge, 0);
FullSubentityPath path = new FullSubentityPath(ids, index);

tmpEnt.Highlight(path, true);

bool PromptCancel = false;

PromptPointOptions FPOption = new PromptPointOptions("Ersten Punkt angeben");
FPOption.Message = "Anfangspunkt zeigen";
PromptPointResult FPResult = null;

while (FPResult.Status == PromptStatus.Error)
{
FPResult = ed.GetPoint(FPOption);
FPOption.Message = "\nFalsche Eingabe. Richtung zeigen";
}

if (FPResult.Status == PromptStatus.Cancel)
PromptCancel = true;

if (FPResult.Status == PromptStatus.OK)
{
Point3d tmpStartPoint = FPResult.Value;
FirstPoint = CurveObj.GetClosestPointTo(tmpStartPoint, false);
DistFP = CurveObj.GetDistAtPoint(FirstPoint);
}

if (!PromptCancel)
{
PromptPointOptions SPOption = new PromptPointOptions("Zweiten Punkt angeben");
SPOption.BasePoint = FirstPoint;
SPOption.UseBasePoint = true;
SPOption.UseDashedLine = true;
SPOption.Message = "Richtung zeigen";
PromptPointResult SPResult = null;

while (SPResult.Status == PromptStatus.Error)
{
SPResult = ed.GetPoint(SPOption);
SPOption.Message = "\nFalsche Eingabe. Richtung zeigen";
}

if (SPResult.Status == PromptStatus.Cancel)
return;

if (SPResult.Status == PromptStatus.OK &&
FPResult.Status == PromptStatus.OK)
{
Point3d tmpDirectionPoint = SPResult.Value;
SecondPoint = CurveObj.GetClosestPointTo(tmpDirectionPoint, false);
DistSP = CurveObj.GetDistAtPoint(SecondPoint);
}

}

tmpEnt.Unhighlight(path, false);

}
}
}
Thread.CurrentThread.CurrentCulture = new CultureInfo("en-us");
DistFPPrompt = DistFP.ToString("F" + Luprec.ToString());
DistSPPrompt = DistSP.ToString("F" + Luprec.ToString());
Dist = Math.Abs(DistSP - DistFP);
DistPrompt = Dist.ToString("F" + Luprec.ToString());

ed.WriteMessage(String.Format("\rAbstand = {0}, erster Punkt = {1}, zweiter Punkt = {2}",
DistPrompt, DistFPPrompt, DistSPPrompt));
acedSetDynInputDisplayMessage(true);

myT.Commit();
}
catch (System.Exception)
{
myT.Commit();
throw;
}

finally
{
myT.Dispose();
}

}

}
}[/code]

Re: Error System.NullReferenceException in code - HELP!!!

Anonymous — Wed, 08 Jun 2005 14:39:05 GMT

I've got it, it was just a silly mistake.

Changed:
[code] while (ent.Status == PromptStatus.Error)
{
ent = ed.GetEntity(entopts);
}[/code]
To:
[code] do
{
ent = ed.GetEntity(entopts);
} while (ent.Status == PromptStatus.Error);[/code]

and so on.

Roland

topic Error System.NullReferenceException in code - HELP!!! in .NET Forum

Error System.NullReferenceException in code - HELP!!!

Re: Error System.NullReferenceException in code - HELP!!!