asp.net - C# The process cannot access the file ''' because it is being used by another process

Question

The snippet of code was just supposed to write a string into a text file called "all_results.txt". I had errors implementing in File.WriteAllText. After searching the net for solutions, I tried using FileStream and StreamWriter as substitutes. The problem still persists.

It gave me:

IOException Unhandled: The process cannot access the file 'C:UsersMadDebaterDesktopConsoleTest1ConsoleTestinDebugall_results.txt' because it is being used by another process.

Strangely, the errors occurs arbitrarily. It could be during the 3rd loop, or 45th loop before it hits an error. I provided the full code for that class in case the problem is deeper than it seems. I'm sure it has nothing to do with my virus scanner or anything like that.

try
                {
                    using (FileStream stream = new FileStream(@"all_results.txt", FileMode.Create)) // Exception here
                {
                    using (StreamWriter writer = new StreamWriter(stream))
                    {
                        writer.WriteLine(result);
                        writer.Dispose();
                        writer.Close();
                    }

                    stream.Dispose();
                    stream.Close();
                }

                }
                catch (IOException ex)
                {
                    Console.WriteLine(ex);
                }

Even when I try this, it still fails.

try
                {
                    File.WriteAllText(@"all_results.txt", result); // Exception here
                }
                catch (IOException ex)
                {
                    Console.WriteLine(ex.Message);
                }

Below is the full code for the class. It is meant to take in a list of Twitter tweets and classify them using Bayes Classification one by one.

    using System;
    using System.IO;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using BayesClassifier;
    using System.Text.RegularExpressions;

    namespace ConsoleTest
    {
        class Analyzer
        {
            public static void Analyzing(List<string> all_results)
            {

            Reducting(all_results);
            Classifying();
        }

        public static void Reducting(List<string> all_results)
        {
            //Reductor
            //Precondition: List<string> results
            all_results.ForEach(delegate(String text)
            {

                const string ScreenNamePattern = @"@([A-Za-z0-9-_&;]+)";
                const string HashTagPattern = @"#([A-Za-z0-9-_&;]+)";
                const string HyperLinkPattern = @"(http://S+)s?";
                string result = text;

                if (result.Contains("http://"))
                {
                    var links = new List<string>();
                    foreach (Match match in Regex.Matches(result, HyperLinkPattern))
                    {
                        var url = match.Groups[1].Value;
                        if (!links.Contains(url))
                        {
                            links.Add(url);
                            result = result.Replace(url, String.Format(""));
                        }
                    }
                }

                if (result.Contains("@"))
                {
                    var names = new List<string>();
                    foreach (Match match in Regex.Matches(result, ScreenNamePattern))
                    {
                        var screenName = match.Groups[1].Value;
                        if (!names.Contains(screenName))
                        {
                            names.Add(screenName);
                            result = result.Replace("@" + screenName,
                               String.Format(""));
                        }
                    }
                }

                if (result.Contains("#"))
                {
                    var names = new List<string>();
                    foreach (Match match in Regex.Matches(result, HashTagPattern))
                    {
                        var hashTag = match.Groups[1].Value;
                        if (!names.Contains(hashTag))
                        {
                            names.Add(hashTag);
                            result = result.Replace("#" + hashTag,
                               String.Format(""));
                        }
                    }
                }

                // Write into text file
/*
                try
                {
                    using (FileStream stream = new FileStream(@"all_results.txt", FileMode.Create)) // Exception here
                {
                    using (StreamWriter writer = new StreamWriter(stream))
                    {
                        writer.WriteLine(result);
                        writer.Dispose();
                        writer.Close();
                    }

                    stream.Dispose();
                    stream.Close();
                }

                }
                catch (IOException ex)
                {
                    Console.WriteLine(ex);
                }
                */
                try
                {
                    File.WriteAllText(@"all_results.txt", result); // Exception here
                }
                catch (IOException ex)
                {
                    Console.WriteLine(ex.Message);
                }

            });
        }

        public static void Classifying()
        {
            // Classifying

            BayesClassifier.Classifier m_Classifier = new BayesClassifier.Classifier();


            m_Classifier.TeachCategory("Positive", new System.IO.StreamReader("POSfile.txt"));
            m_Classifier.TeachCategory("Negative", new System.IO.StreamReader("NEGfile.txt"));

            Dictionary<string, double> newscore;
            newscore = m_Classifier.Classify(new System.IO.StreamReader("all_results.txt"));

            PrintResults(newscore);
}

        public static void PrintResults(Dictionary<string, double> newscore)
        {
            foreach (KeyValuePair<string, double> p in newscore)
            {
                Console.WriteLine(p.Key + ", " + p.Value);
            }

            List<string> list = new List<string>();
            using (StreamReader reader = new StreamReader("all_results.txt"))
            {
                string line;
                while ((line = reader.ReadLine()) != null)
                {
                    list.Add(line);          // Add to list.
                    Console.WriteLine(line); // Write to console.

                }

                reader.Close();
            }

            //PrintSentiment(newscore);
        }

        public static void PrintSentiment(Dictionary<string, double> newscore)
        {

            // if difference < 2, neutral
            // if neg < pos, pos
            // if pos < neg, neg

            double pos = newscore["Positive"];
            double neg = newscore["Negative"];
            string sentiment = "";

            if (Math.Abs(pos - neg) < 1.03)
            {
                sentiment = "NEUTRAL";
            }
            else
            {
                if (neg < pos)
                {
                    sentiment = "POSITIVE";
                }
                else if (pos < neg)
                {
                    sentiment = "NEGATIVE";
                }
            }

            Console.WriteLine(sentiment);


            // append tweet_collection to final_results <string> list
            // append sentiment tag to the final_results <string> list
            // recursive
        }
    }
}

Answer 1

Dont call Dispose() and Close() on the FileStream and StreamWriter, this will be handled automatically by the using-clause.