File used twice in a row synchronously

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In my application at first start I create a text file in isolated storage

C#

isoStore.CreateFile("MyApp\\Memo.txt");

and at launching I do this (memoPrices is a List<string> that keeps some prices):

C#

public static async void FillPricesFromIsoStore()
{
    using (IsolatedStorageFile isoStore = IsolatedStorageFile.GetUserStoreForApplication())
    {
        if (isoStore.FileExists("MarketApp\\Memo.txt"))
        {
            try
            {
                IsolatedStorageFileStream fileStream = new IsolatedStorageFileStream("MarketApp\\Memo.txt", FileMode.Open, isoStore);
                using (StreamReader file = new StreamReader(fileStream))
                {
                    String input = await file.ReadLineAsync();
                    while (input != null)
                    {
                        memoPrices.Add(input);
                        input = await file.ReadLineAsync();
                    }
                    file.Close();
                }
            }
            catch(Exception e)
            {
                // I added just this because e.InnerException doesn't return anything
                System.Diagnostics.Debug.WriteLine(e.ToString());
            }
        }
    }
}

At the first start of the app I catch an exception that says that I can't use the file because it is used in other place, that place is where it is created.
This is the output of the catch block:

C#

System.IO.IsolatedStorage.IsolatedStorageException: Operation not permitted on IsolatedStorageFileStream.
   at System.IO.IsolatedStorage.IsolatedStorageFileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, IsolatedStorageFile isf)
   at System.IO.IsolatedStorage.IsolatedStorageFileStream..ctor(String path, FileMode mode, IsolatedStorageFile isf)
   at MarketApp.ShortTimeStoring.<FillPricesFromIsoStore>d__0.MoveNext()

What I have tried:

I tried to call the method repeatedly until the file is usable.

Posted 16-Mar-16 12:34pm

Ionascut Mihai

Updated 18-Mar-16 3:29am

v4

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Comments

ZurdoDev 16-Mar-16 21:03pm

InnerException is often null but its just a property of the exception.

Sergey Alexandrovich Kryukov 16-Mar-16 21:29pm

His previous questions indicates that, in that case, having an inner exception is very likely. Anyway, I credited your correct comment in my answer.
—SA

Ionascut Mihai 17-Mar-16 18:12pm

I added more breakpoints in my app and I realized that the exception isn't appearing where I thought. I edited my question and I explain the problem again. Can you look again and tell me if it's ok?

Sergey Alexandrovich Kryukov 17-Mar-16 19:10pm

Again, you did not provide a single line of code using the property "InnerException". So, what to talk about? Now, if you cannot find out where the exception is throw, simply catch it upper on stack. Do you even understand that exceptions propagate back toward top of stack to each nearest handler? Of course, it's per thread.
—SA

Ionascut Mihai 18-Mar-16 0:52am

I done it on my computer. You told me to add at catch block Exception.ToString() or Exception.InnerException. I added them and both indicates me that the problem is in that lines of code. I didn't post it here with that changes because the inner is very explicit about the problem and where it happeneds. I added in my code what you said in catch block and post the output

Sergey Alexandrovich Kryukov 18-Mar-16 1:10am

Look, you want to get help and it sounds like you want to keep some code in secret? Very funny.
Good day.
—SA

Ionascut Mihai 18-Mar-16 9:51am

@Sergey This is only the part of code where I occur problems. Thank you for your time and help, but you do not consider me stupid because I know how to read an exception if I have it. Again thank you! :)

Sergey Alexandrovich Kryukov 18-Mar-16 18:28pm

No, I don't consider you stupid, but you act quite passively. You do need to write and present code; and it should not be the code of your "real" application; you can create a minimalistic prototype project focusing on just one problem... I hope you got the solution, haven't you?
—SA

Ionascut Mihai 19-Mar-16 5:56am

Then sorry about my reaction. Yes, I got it. I will keep in mind what you told about the code

Sergey Alexandrovich Kryukov 19-Mar-16 19:33pm

Great. Nothing to be sorry about, no problems at all...
—SA

2 solutions

Solution 1

It has nothing to do with Visual Studio 2013 or any particular IDE. This is a fundamental feature of .NET. It probably won't be too strong saying that if you don't use it, you are going nowhere.

All you need is this:
Exception Class (System)[^],
Exception.InnerException Property (System)[^].

During debugging, you can always insert some debug code which catches your exception and tries to examine the inner exception referenced by it, and so on, recursively. Moreover, this information is added to Exception.ToString() result. Note also the comment by RyanDev. Of course, do do any programming at all, you have to clearly understand how exceptions work and how they can be used. (If not your confused state of mind revealed by your last two questions, I would not question your knowlege of this matter.) For a really short introduction, I can offer my past answers:
Does Exception in C# Constructor Cause Caller Assignment to Fail?[^],
where was stored .net exceptions in operating system[^],
Image taken from Webcam not getting saved on the server[^].

—SA

Posted 16-Mar-16 15:27pm

Sergey Alexandrovich Kryukov

Updated 17-Mar-16 13:06pm

v2

Comments

[no name] 17-Mar-16 18:52pm

A 5 to give a hint once more again about exception handling in .NET
Bruno

Sergey Alexandrovich Kryukov 17-Mar-16 19:06pm

Thank you, Bruno.
—SA

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Richard Deeming · Accepted Answer · 2016-03-18T03:29:00

The IsolatedStorageFile.CreateFile method[^] returns an IsolatedStorageFileStream. You haven't shown the relevant parts of your code, but I suspect you forgot to close / dispose that stream, which means the file is still open.

Change the code that creates the file to close the stream when you're finished with it:

C#

using (var stream = isoStore.CreateFile("MyApp\\Memo.txt"))
{
    // Initialize the file contents here...
}

You should also change the FillPricesFromIsoStore method to wrap the stream in a using block:

C#

using (var fileStream = isoStore.OpenFile("MarketApp\\Memo.txt", FileMode.Open))
using (StreamReader file = new StreamReader(fileStream))
{
    ...
}

File used twice in a row synchronously

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Solution 1

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File used twice in a row synchronously

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Solution 1

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