Enumeration already finished

Question

I got an Error an enumeration already finish. How to check if an enumeration already finished?

Vulpes · Answer

The only thing that strikes me there is that there's plenty of scope for the regular expression to go wrong. For example, if the string contained 'on' or 'ON' rather than 'On'. If there was more than one occurrence (or no occurrences) of 'On' and 'Off' in the same string. If 'On' or 'Off' was not preceded by a space etc. As long as you're comparing two enum values of the same type (which I can now see is the case), then there's no need to cast to int first. So this should work OK as both operands are of type ColorTimeType: if (prevColorOn.Type != ColorTimeType.On) { throw new ArgumentException("prevColorOn.Type", "Did not recieved expected ColorTimeType 'prevColorOn'."); }

David Smith · Answer

Vuples here a code snippet of what I am doing. I cut a lot of code out, so some code is missing. But this will answer your question of what I am doing in the function or what the Color object I created is below. private static Color GetColorInfo(string colorInfo) { try { const string FORMAT_SEQUENCE = "(^.+) (On|Off)"; Regex r = new Regex(FORMAT_SEQUENCE); Match match = r.Match(colorInfo); Color color = new Color(); color.ColorDateTime = dt; color.ColorType = (match.Groups[2].ToString() == "On") ? ColorTimeType.On : ColorTimeType.Off; return cycle; } catch( Exception) { throw; } } --------------------------------------------------- This enumeration comparison below works, is there another way to do it without using the integer value of the enumeration type. prevColorOn = GetColorInfo((string)en.Current); if ((int)prevColorOn.Type != (int)ColorTimeType.On) { throw new ArgumentException("prevColorOn.Type", "Did not recieved expected ColorTimeType 'prevColorOn'."); }

Vulpes · Answer

I assume that your Color type can't be the same as System.Drawing.Color because the latter doesn't have a Type property. If Color and ColorType are both enums, then I don't know how that line is even compiling because you can't use the inequality operator (!=) with operands of different enum types. So I imagine therefore that Color is probably a class or struct which has a Type property of type ColorType which is an enum. But, other than that, I can't really comment on why it's not behaving as expected because I don't know how GetCycleInfo is setting the Type property of the Color instance it's returning.

David Smith · Answer

Ok. I am going to try that right now. Also below I am try to compare Enumeration value, for some reason the statement is dropping into the condition which is not valid. Because the value equal each when I step into the code. if (prevColorOn.Type != ColorType.ColorOn) { throw new ArgumentException("prevColorOn", "Did not recieved expected ColorType'prevColorOn'."); }

Vulpes · Answer

Well, I can't see any signs of the collection being modified in that snippet so it looks like the exception is being thrown when you attempt to access en.Current after the enumeration has finished. Usually, this property is left undefined and no exception is thrown but it looks like this particular enumerator has been coded to thrown an exception instead. If the snippet is within a void method, then you could prevent the Current property being accessed when the enumeration has finished by replacing (wherever it occurs): en.MoveNext(); with: if (!en.MoveNext()) return; However, you may want to take some further action before the method returns.

David Smith · Answer

Below is a snippet of what I am doing. Basically when I enumerate to go information is not there I get the error below in red. Vuples how to know if the enumeration has not finished or finished so I can do something when I get a response? Color prevColorOn; Color prevColorOff; IEnumerator en = dataSetList.GetEnumerator(); en.MoveNext(); prevOn = GetCycleInfo((string)en.Current); if (prevColorOn.Type != ColorType.On) { throw new ArgumentException("prevColorOn.Type"); } en.MoveNext(); prevColorOff = GetCycleInfo((string)en.Current); //Enumeration already finished if (prevColorOff.Type != ColorType.Off) { throw new ArgumentException("prevColorOff.Type"); } double ColorTimeUsed = (prevColor1.TimeTag - prevColor2.TimeTag).TotalSeconds; for (int i = 0; i { en.MoveNext(); Color newColorOn = GetColorInfo((string)en.Current); en.MoveNext(); Color newColorOff = GetColorInfo((string)en.Current); }

Vulpes · Answer

Well, normally you'd know if the collection were being modified (by adding, changing or deleting elements) whilst you were enumerating it and could therefore refrain from doing so. Is it therefore possible that the collection is being modified on a different thread or by some process which you can't control directly?

Jignesh Trivedi · Answer

hi, MoveNext() method return true or false try IEnumerator en = dataSetList.GetEnumerator(); while (en.MoveNext()) { // do your code. var myData = en.Current; } Please refer http://msdn.microsoft.com/en-us/library/system.collections.ienumerator.movenext.aspx hope this will help you.

David Smith · Answer

How to handle the collection from being modified vuples?

Vulpes · Answer

When an enumeration finishes, MoveNext will return false and will keep on returning false if you call it again. However, if you're getting an InvalidOperationException, that suggests that the collection is being modified in some way while it's being enumerated which is not allowed.

David Smith · Answer

IEnumerator en = dataSetList.GetEnumerator(); en.MoveNext(); Just an example, if I keep trying to MoveNext, I will eventually get an Enumeration has already finished error.

Hemant Srivastava · Answer

Can you provide some more details with code?

Enumeration already finished

Answers (12)