"activator.createinstance()" gives error when try to run - c#

I was unable to solve the following error. I'll appreciate your help.
I have the following class:
public class GB
{
private StreamReader sr;
public GB()
{
sr = new StreamReader(new FileStream("C:\\temp.txt", FileMode.Open, FileAccess.ReadWrite));
}
public int MultiCall()
{
if (sr.ReadLine() == "test1")
return 1;
else
return 0;
}
}
in my form, there is button with the following function;
void buttonClick()
{
myAssembly = Assembly.LoadFrom(dllpath); // dllpath is the dll file for GB class
myType = myAssembly .GetType("GB");
myObject = Activator.CreateInstance(myType);
myMethodInfo = myType .GetMethod("MultiCall");
returnValue = myMethodInfo.Invoke(myObject, null);
myObject = null;
}
Here is my question; When i click the button for the first time, Everything is OK. But when i click it again i get the following error;
The process cannot access the file 'C:\temp.txt' because it is being used by another process.
The object returned from activator.createinstance doesnot seem to be nulled after first call. Although i assign it to a null value by myObject = null i still get the same error. Any ideas?
thx.

The constructor of GB opens a ReadWrite stream to the file, but then never closes it. The subsequent invocation of GB attempts to open the same file, but this obviously fails.
What you need to do is implement IDisposable on GB, which disposes of the StreamReader, e.g.:
public class GB : IDisposable
{
private StreamReader sr;
private bool _isDisposed;
public GB()
{
sr = new StreamReader(new FileStream("C:\\temp.txt", FileMode.Open, FileAccess.ReadWrite));
}
public int MultiCall()
{
if (sr.ReadLine() == "test1")
return 1;
else
return 0;
}
~GB()
{
Dispose(false);
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
private void Dispose(bool isManaged)
{
if(_isDisposed)
return;
if(isManaged)
{
// Ensure we close the file stream
sr.Dispose();
}
_isDisposed = true;
}
}
Then dispose of your GB instance once you are done with it.
// Dispose of the GB instance (which closes the file stream)
var asDisposable = (IDisposable)myObject;
asDisposable.Dispose();
IDisposable exists for exactly this reason, to ensure unmanaged resources are successfully released.

Store the value returned by the file then check it value in the MultiCall method. This way you file gets closed and disposed for you.
public class GB
{
private string str;
public GB()
{
using (var sr = new StreamReader(new FileStream("C:\\temp.txt", FileMode.Open, FileAccess.ReadWrite)))
{
str = sr.ReadToEnd();
}
}
public int MultiCall()
{
if (str == "test1")
return 1;
else
return 0;
}
}

Related

Unity3D Save or Load each Level and their own variables

I am new to stackoverflow and to Unity3D, so I am sorry if I am doing things wrong.
So currently, I am making a puzzle game. It has 50 different levels.
I need for each of them, to save 3 or 4 variables.
For example, when level 1 is cleared, I want it to store (int)hitCounts, (bool)cleared, (int)bestHitCounts.
I don't wanna use playerPrefs, as I don't want it to be readable from outside the box. I want it be converted to a binary file.
here is what I have :
#1 : made a static class TGameDat
[System.Serializable]
public class TGameDat
{
public int tGameDatInt;
public bool tGameDatBool;
public int tSceneIndex;
public TGameDat (TPlayer player)
{
tGameDatInt = player.tInt;
tGameDatBool = player.tBool;
tSceneIndex = player.tScene;
}
}
#2 : then made Tplayer(monobehaviour)
public class TPlayer : MonoBehaviour
{
public int tInt = 0;
public bool tBool = false;
public int tScene;
public List<TPlayer> TestGameDatList = new List<TPlayer>();
private void Start()
{
TSceneMaker();
}
public void TSceneMaker()
{
tScene = SceneManager.GetActiveScene().buildIndex;
}
public void TNextScene()
{
SceneManager.LoadScene(tScene + 1);
}
public void TPreviousScene()
{
SceneManager.LoadScene(tScene - 1);
}
public void TSaveVariables()
{
TSave.TSavePlayer(this);
TestGameDatList.Add(this);
Debug.Log("saved");
Debug.Log(tInt + " " + tBool + " " + tScene);
}
public void TLoadVariables()
{
List<TGameDat> data = TSave.TLoadPlayer(this);
Debug.Log("loaded. data count = " + data.Count + " tSceneIndex " + tScene);
tInt = data[0].tGameDatInt;
tBool = data[0].tGameDatBool;
tScene = data[0].tSceneIndex;
}
}
#3 : finally I created a save and load system :
public static class TSave
{
public static void TSavePlayer (TPlayer player)
{
BinaryFormatter formatter = new BinaryFormatter();
List<TGameDat> data = new List<TGameDat>();
string path = Application.persistentDataPath + "/Tsave_" + player.tScene + ".fun";
if(File.Exists(path))
{
FileStream stream = File.Open(path, FileMode.Open);
data.Add(new TGameDat(player));
formatter.Serialize(stream, data);
stream.Close();
}
else
{
FileStream stream = File.Create(path);
data.Add(new TGameDat(player));
formatter.Serialize(stream, data);
stream.Close();
}
}
public static List<TGameDat> TLoadPlayer(TPlayer player)
{
string path = Application.persistentDataPath + "/Tsave_" + player.tScene + ".fun";
if(File.Exists(path))
{
BinaryFormatter formatter = new BinaryFormatter();
FileStream stream = File.Open(path, FileMode.Open);
List<TGameDat> data = new List<TGameDat>();
data = formatter.Deserialize(stream) as List<TGameDat>;
stream.Close();
return data;
}
else
{
Debug.LogError("Save file not found in " + path);
return null;
}
}
}
So, here are my problems :
1 : in the current situation, each scene compiles a binary file. So at the end, it will have a bunch of binary files piled up... Like 50, as I have 50 scenes... isn't it too many?
2 : of course I tried the make a single save file using List, and each level would come to add its own variable data in it.
But instead of adding the data, it would simply replace the previous data. Then there is always only 1 index in the List.
Therefore, when I load, the variables are from the last played level! And when I try to play another level after playing the first level, because there is only 1 index in the list, I get out of range error.
How shall I approach this?
sorry for the long long text!
thank you for your inputs!
first thing first, do you really need every level to have its own save data? Because if you only need to store the data between one level and another I would suggest you use some kind of PlayerState class that stores the data of the previous level.
But if you really need to store the data of every level then I'll recommend you using a dictionary rather than a simple list.
Here is an example of how I would do it
Note: I haven't tested this code yet!
SaveGameManager class
public string SavePath => Application.persistentDataPath + "/save.dat";
public static SaveGameManager Instance; // Singleton pattern
private Dictionary<string, TGameDat> gameData;
private void Awake()
{
if (Instance != null)
{
Destroy(this.gameObject);
return;
}
// Singleton initialization
Instance = this;
// Keep the object when changing scenes
DontDestroyOnLoad(this.gameObject);
LoadGameData();
}
public TGameDat GetGameData(string key)
{
if (gameData.TryGetValue(key, out TGameDat data))
{
return data;
}
Debug.Log($"Unable to find saved data with key {key}");
return null;
}
public void SetGameData(string key, TGameDat data)
{
// Sets a value with given key and save it to file
gameData[key] = data;
SaveGameData();
}
public void SaveGameData()
{
Serializer.SaveBinaryFile(gameData, SavePath);
}
public void LoadGameData()
{
var savedData = Serializer.LoadBinaryFile(SavePath);
if (savedData != null)
{
gameData = (Dictionary<string, TGameDat>)savedData;
}
else
{
// Creating and saving new data because we can't found
// any that already stored in path
gameData = new Dictionary<string, TGameDat>();
SaveGameData();
}
}
And then, the Serializer class
public static void SaveBinaryFile(object data, string path)
{
using (var stream = new FileStream(path, FileMode.Create))
{
var formatter = new BinaryFormatter();
formatter.Serialize(stream, data);
}
}
public static object LoadBinaryFile(string path)
{
if (!File.Exists(path))
{
// Trying to load a file that does not exist
return null;
}
using (var stream = new FileStream(path, FileMode.Open))
{
var formatter = new BinaryFormatter();
return formatter.Deserialize(stream);
}
}
And then you can use it like this
public TGameDat data;
public void TSaveVariables()
{
SaveGameManager.Instance.SetGameData(level.id, this.data);
}
public void TLoadVariables()
{
var savedData = SaveGameManager.Instance.GetGameData(level.id);
if (savedData != null)
{
this.data = savedData;
}
else
{
// We don't have any save file for this level yet
savedData = new TGameDat();
}
}
You can change level.id to whatever identifier you wanted to use.

Is there a construct or pattern similar to C# `using` which will return an object?

I have a WCF message inspector which inspects requests and responses: Message. The inspector works fine. A Message object can only be read once so once you read it, you cannot simply propagate as WCF will complain that the message has been read. Therefore, I am creating a brand new copy of the message and propagating that.
I have designed a class that allows message reading and after the caller has read whatever they want, they need to call Close which will return a copy of the message. Here is the skeleton of my class:
using System.ServiceModel.Channels;
internal abstract class MessageReader
{
internal string ReadSomething(string id)
{
// Return string
}
internal string ReadSomethingElse(string id)
{
// Return string
}
internal Message Close()
{
// Create copy and return it.
}
}
Users of my class may forget to call Close() which is fine because WCF will yell at them. Right now I have documentation to let users know they need to call Close().
Here is the question
Is there a pattern, or something similar, to C#'s using construct but one which returns an object at the end? This will be really convenient because then users of my class can just use a construct like that and at the end it will return the copy of the message. Something like this:
UsingSomeConstruct(var reader = new MessageReader(ref originalMessage))
{
var a = reader.ReadSomething("something");
var b = reader.ReadSomethingElse("something");
// Do something with what was read
}
// At this point originalMessage will be the copy of the message and no longer the original message.
EDIT
I thought about hacking IDisposable to achieve this but I am NOT going to do it that way so looking for other ideas.
There is no such language construct of course.
What I could suggest is to use IDisposable for cleaning up, and add ref Message message argument to each ReadXXX method. I know it will not be so convenient for your users, but from the other side they cannot forget passing the parameter.
So the implementation would be something like this:
internal class MessageReader : IDisposable
{
private MessageBuffer buffer;
private Message message;
private void Release()
{
if (buffer == null) return;
buffer.Close();
buffer = null;
message = null;
}
protected void OnReadRequest(ref Message message)
{
if (message == null) throw new ArgumentNullException("message");
if (this.message == message) return;
Release();
this.buffer = message.CreateBufferedCopy(int.MaxValue);
message = this.message = buffer.CreateMessage();
}
public void Dispose()
{
Release();
}
internal string ReadSomething(ref Message message, string id)
{
OnReadRequest(ref message);
// Return string
}
internal string ReadSomethingElse(ref Message message, string id)
{
OnReadRequest(ref message);
// Return string
}
}
and the sample usage:
using (var reader = new MessageReader())
{
var a = reader.ReadSomething(ref originalMessage, "something");
var b = reader.ReadSomethingElse(ref originalMessage, "something");
// Do something with what was read
}
// At this point originalMessage will be the copy of the message and no longer the original message.
The way I'd do this is as follows:
public MessageReader: IDisposable
{
public static MessageReader Create(ref Message message)
{
var buffer = message.CreateBufferedCopy(/*whatever is fit*/);
try
{
var reader = new MessageReader(buffer);
message = buffer.CreateMessage();
return reader;
}
catch
{
buffer.Close();
throw;
}
}
private readonly MessageBuffer buffer;
private bool disposed;
private MessageReader(MessageBuffer buffer) { this.buffer = buffer; }
public void Dispose()
{
if (disposed)
return;
buffer.Close();
disposed = true;
}
public string Read(string id)
{
var newCopy = buffer.CreateMessage();
//work with new copy...
}
}
And you'd simply use it like this:
using (var reader = MessageReader.Create(ref message))
//message here is already an untouched copy with no need of user active
//intervention and is never touched again by the reader.
{
var a = reader.Read("something"); //reads copy
...
}
IMHO, this is as clean as it can be. Note that MessageReader implements IDisposable exclusively because it holds a reference to the disposable private MessageBuffer.
Thanks to all the help from #InBetween, #quetzalcoatl, and #Ivan Stoev. Upvoted your answers because it helped me arrive at the following.
In the constructor, I create a copy of the message and set the original message to the copy. Since the status of this message is Created WCF will be happy propogating it. I create another copy and use that for reading multiple times.
#Ivan said but what if the user does not ask for anything to be read then the copying was wasted work. That is a good point but in my case, this is an interceptor and all messages are intercepted to be read.
Here is the code I ended up with suggestions from all of you:
public class MessageReader : IDisposable {
private readonly Message message;
public MessageReader(ref Message originalMessage) {
using( var buffer = originalMessage.CreateBufferedCopy( int.MaxValue ) ) {
// Keep original message for reading
this.message = buffer.CreateMessage();
// Set original message to a copy of the original
originalMessage = buffer.CreateMessage();
}
}
public int ReadSomething(string id) {
// Read from this.message;
}
public int ReadSomethingElse(string id) {
// Read from this.message;
}
public void Close() {
this.Dispose();
}
public void Dispose() {
this.message.Close();
}
}
The caller can either use it in a using block or without it. The using block is used for good reasons and not as a hack.
public object AfterReceiveRequest(ref Message request, IClientChannel channel,
InstanceContext instanceContext) {
try {
using( var rdr = new MessageReader(ref request) ) {
var value= rdr.ReadSomething( someIdentifier );
return value;
}
}
catch( System.Exception ex ) {
throw CreateFault( ex, request );
}
}
Nope, there is no such construct. It is simply too specific to exist there out of the box. There are extension methods which often are very helpful, but you won't be able to use them on this ref Message parameter..
However, if you are willing to use ref at all, then why dont simply include all that logic it in Reader's constructor?
Here's an example, somewhat contrived, but it should show what I mean. Like others mentioned in comments, I also suggest implementing IDisposable on the Reader object instead of Close, so I included that already.
TL;DR: In example below, the most important thing is in Reader(ref msg) constructor which clones the message, copies the data, and replaces the original message with a safe-message class which can be read many times..
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
namespace Rextester
{
public class Program
{
public static void Main(string[] args)
{
// real-world variables, keep them typed as base Message
// to be able to silently replace them with different objects
Message original1;
Message original2;
// let's construct some one-time readable messages
{
var tmp1 = new OneTimeMessage();
tmp1.data["mom"] = "dad";
tmp1.data["cat"] = "dog";
original1 = tmp1;
var tmp2 = new OneTimeMessage();
tmp2.data["mom"] = "dad";
tmp2.data["cat"] = "dog";
original2 = tmp2;
}
// test1 - can't read twice
Console.WriteLine("test0A:" + original1.GetData("mom"));
//Console.WriteLine("test0B:" + original1.GetData("mom")); // fail
// test2 - can read twice with Reader's help
var backup1 = original2;
using(var rd1 = new Reader(ref original2))
{
Console.WriteLine("test1A:" + rd1.ReadSomething("mom"));
}
var backup2 = original2;
using(var rd2 = new Reader(ref original2))
{
Console.WriteLine("test1A:" + rd2.ReadSomething("mom"));
//^ ok - becase Reader replaced 'original2' with SafeMessage
}
// test3: Reader's ctor is intelligent
// so no more SafeMessages created during future usage
var backup3 = original2;
using(var rd3 = new Reader(ref original2))
{
}
var backup4 = original2;
using(var rd4 = new Reader(ref original2))
{
}
Console.WriteLine("checking for copies:" + (original2 == backup1));
Console.WriteLine("checking for copies:" + (original2 == backup2));
Console.WriteLine("checking for copies:" + (original2 == backup3));
Console.WriteLine("checking for copies:" + (original2 == backup4));
}
}
}
public abstract class Message
{
public abstract string GetData(string id);
}
public class OneTimeMessage : Message // this models your current one-time-readable message
{
public IDictionary<string, string> data = new Dictionary<string, string>();
public override string GetData(string id)
{
var tmp = data[id];
data.Remove(id);
// that's nonsense, but I want to show that you can't
// read the same thing twice from this object
return tmp;
}
}
public class SafeMessage : Message
{
public IDictionary<string, string> data;
public override String GetData(string id)
{
return data[id];
}
public SafeMessage(Message msg)
{
// read out the full msg's data and store it
// since this is example, we can do it in a pretty simple way
// in your code that will probably be more complex
this.data = new Dictionary<string,string>(((OneTimeMessage)msg).data);
}
}
public class Reader : IDisposable
{
private Message message;
public Reader(ref Message src)
{
src = src is SafeMessage ? src : new SafeMessage(src);
this.message = src;
}
public string ReadSomething(string id){ return message.GetData(id); }
public void Dispose(){ Close(); }
public void Close(){ message=null; Console.WriteLine("reader closed"); }
}
EDIT: improved example
using System;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel.Channels;
using System.Text.RegularExpressions;
using System.Xml;
namespace MyProgram
{
public class Program
{
public static void Main(string[] args)
{
// real-world variables, keep them typed as base Message
// to be able to silently replace them with different objects
Message original1;
Message original2;
// let's construct some one-time readable messages
{
original1 = new TheMessage("dad", "dog");
original2 = new TheMessage("dad", "dog");
}
// test1 - can't read twice
Console.WriteLine("test0A:" + original1.GetReaderAtBodyContents().ReadOuterXml());
// Console.WriteLine("test0B:" + original1.GetReaderAtBodyContents().ReadOuterXml()); // fail: InvalidOperationException - it was already read
// test2 - can read ONCE with Reader's help, but the message is replaced and is usable again
var backup1 = original2;
using (var rd1 = new ReaderOnce(ref original2))
{
Console.WriteLine("is message replaced after opening Reader:" + (original2 != backup1));
Console.WriteLine("test1A:" + rd1.ReadBodyXml());
// Console.WriteLine("test1B:" + rd1.ReadBodyXml()); // fail: InvalidOperationException - it was already read
}
// test3 - can read MANY TIMES with ReaderMany's help
// also note we use 'original2' again, which was already used above, so in fact ReaderOnce really works as well
var backup2 = original2;
using (var rd1 = new ReaderMany(ref original2))
{
Console.WriteLine("is message replaced after opening Reader:" + (original2 != backup2));
Console.WriteLine("test2A:" + rd1.ReadBodyXml());
Console.WriteLine("test2B:" + rd1.ReadBodyXml()); // ok
}
Console.WriteLine("Press enter to exit");
Console.ReadLine();
}
}
}
// solution1
public class ReaderOnce : IDisposable
{
private Message localCopy;
public ReaderOnce(ref Message src)
{
// create a WCF MessageBuffer to assist in copying messages
// btw. I suppose you should set some sane limit instead of that below
using (var tempBuffer = src.CreateBufferedCopy(int.MaxValue))
{
src = tempBuffer.CreateMessage(); // FIRST copy for outer use
localCopy = tempBuffer.CreateMessage(); // SECOND copy for internal use in the Reader
}
}
public void Dispose() { Close(); }
public void Close()
{
localCopy.Close(); // but that does NOT affect FIRST copy sent to outer scope outside reader
Console.WriteLine("reader closed");
}
public string ReadBodyXml() // careful: that's again ONE TIME readable
{
return localCopy.GetReaderAtBodyContents().ReadOuterXml();
}
}
// solution2
public class ReaderMany : IDisposable
{
private MessageBuffer localBuffer;
public ReaderMany(ref Message src)
{
localBuffer = src.CreateBufferedCopy(int.MaxValue);
src = localBuffer.CreateMessage(); // FIRST copy for outer use
}
public void Dispose() { Close(); }
public void Close()
{
localBuffer.Close();
Console.WriteLine("reader closed");
}
public string ReadBodyXml() // this is readable multiple times
{
using (var tmp = localBuffer.CreateMessage())
return tmp.GetReaderAtBodyContents().ReadOuterXml();
}
}
// let's fake some Message type to have something to test the Reader on
public class TheMessage : Message
{
public override MessageHeaders Headers => _mh;
public override MessageProperties Properties => _mp;
public override MessageVersion Version => _mv;
private MessageHeaders _mh;
private MessageProperties _mp;
private MessageVersion _mv;
private string data1;
private string data2;
// btw. below: surprise! XmlDictionaryWriter is in "System.Runtime.Serialization", not in "System.Xml"
protected override void OnWriteBodyContents(XmlDictionaryWriter writer)
{
writer.WriteStartElement("foo");
writer.WriteAttributeString("data1", data1);
writer.WriteAttributeString("data2", data2);
writer.WriteEndElement();
}
public TheMessage(string data1, string data2)
{
// remember, this class is just an example, you will work on your own messages you already have
_mv = MessageVersion.Soap12;
_mh = new MessageHeaders(_mv);
_mp = new MessageProperties();
// below: yeah, that's super-naive and wrong, but that's an example
this.data1 = data1;
this.data2 = data2;
}
}
There is no language construct in c# that does what you are asking. As stated in comments, you could abuse IDisposable and the language and use a using block to achieve what you want.
But, I fail see what you are gaining, you are just punting the problem; now users will need to remember to use usinginstead of Close. The latter is simple and clean, the former uses a very known language construct to do something different to what it was thought for, something that will potentially be very confusing.

String is null after binary serialization

I'm making a simple game, one of the features is challenges which are going to be opened from a file, here is how one of the challenges look:
[System.Serializable]
public class Challenge10 : ChallegeInterface {
public bool isCompleted = false;
public string description = "test";
public int curCoins;
public override void giveReward (){
GameDataSingleton.gameDataInstance.game_data.addCoinsFromReward (7);
}
//Method to check if everything is completed
public override bool isComplete (){
if (!isCompleted) {
curCoins= GameDataSingleton.gameDataInstance.game_data.getCoinsThisGame ();
if (curCoins >= 1) {
isCompleted = true;
giveReward ();
return true;
}
}
return false;
}
}
The problem is that after I deserielize the file the string value(description) is null. Here is the code where the program is opening the challenges.
public void openChallenges(){
challenges = new ChallegeInterface[game_data.challenges.Length];
for (int i = 0; i < game_data.challenges.Length; i++) {
int curChallenge = game_data.challenges[i];
ChallegeInterface challenge = HddManager.HddManagerInstance.load<ChallegeInterface> ("challenges/challenge"+curChallenge);
Debug.Log (challenge.description);
challenges[i] = challenge;
}
}
Everything else seems fine, except the description. Am i missing something?
Edit:
This is how the program is serializing the object:
public void save<T>(T data, string fileName) where T : class{
if (fileName == "")
Debug.Log ("Empty file path");
FileStream file = null;
try{
if(fileName.IndexOf("/") > 0){
string[] strDirName = fileName.Split(new char[] {'/'});
string dirName = strDirName[0];
if(!Directory.Exists(Path.Combine(Application.persistentDataPath, dirName))){
Directory.CreateDirectory(Path.Combine(Application.persistentDataPath, dirName));
}
}
file = File.Create(Path.Combine(Application.persistentDataPath, fileName));
binFormatter.Serialize(file, data);
Debug.Log ("File saved succesfully" + fileName);
}catch(IOException e){
Debug.Log(e.ToString());
}finally{
if(file != null)
file.Close();
}
}
This is how the object is deserialized:
public T load<T> (string fileName) where T : class{ // T => object type
if (fileName == null) {
Debug.Log ("Empty path to file");
return null;
} else {
FileStream file = null;
try {
//Open the file;
file = File.Open (constructFilePath(fileName), FileMode.Open);
//To be removed
Debug.Log ("File loaded succesfully");
// Deserialize the opened file, cast it to T and return it
return binFormatter.Deserialize (file) as T;
} catch (IOException e) {
//To be removed
Debug.Log (e.ToString ());
// Saves the current object in case the file doesn't exist
// Use Activator to create instance of the object,
save (Activator.CreateInstance<T> (), fileName);
// calls the function again
return load<T> (fileName);
} finally {
//Close the file
if (file != null)
file.Close ();
}
}
}
By inspecting the following lines in the openChallenges() method:
ChallegeInterface challenge = HddManager.HddManagerInstance.load<ChallegeInterface> ("challenges/challenge"+curChallenge);
Debug.Log (challenge.description);
I assume ChallegeInterface is actually a class and not an interface since interfaces can not contain fields and you are accessing challenge.description when challenge is ChallegeInterface which means ChallengeInterface is a class.
In this case you are actually accessing the base class' (ChallegeInterface) field instead of the correct one (Challenge10). and that field is empty.
Important: keep clear and correct coding conventions, never name a class Interface, it's better to avoid naming types with programming terminology instead of indicative naming related to their usage.
P.S.: I've checked the serialization myself and inspected Challenge10's description and it works fine.

Writing unittest to create a file and then delete that file

I have this method I created :
public static bool DeleteFile(FileInfo fileInfo)
{
try
{
fileInfo.Delete();
return true;
}
catch (Exception exception)
{
LogManager.LogError(exception);
return false;
}
}
Now I wrote the following unittest:
[TestMethod]
public void DeleteFileSuccessFul()
{
string fileName = "c:\\Temp\\UnitTest3.txt";
FileInfo fileInfo = new FileInfo(fileName);
File.Create(Path.Combine(fileName));
bool success = FileActions.DeleteFile(fileInfo);
Assert.IsTrue(success);
}
This test fails because the file is in use by a different proces.
The test fails on het bool success = FileActions.DeleteFile(fileInfo); because the file is in use by a different process.
How can I change my test so it works ?
You have to call Dispose method on the FileStream object returned by the File.Create method to release the handle to that file:
[TestMethod]
public void DeleteFileSuccessFul()
{
string fileName = "c:\\Temp\\UnitTest3.txt";
FileInfo fileInfo = new FileInfo(fileName);
using (File.Create(Path.Combine(fileName)))
{
}
bool success = FileActions.DeleteFile(fileInfo);
Assert.IsTrue(success);
}
UPDATE: using block provides a convenient syntax that ensures the Dispose method of an IDisposable object is get called after leaving the scope of the block even if an exception occurs. The equivalent to the above code could be re-written with try-finally block:
[TestMethod]
public void DeleteFileSuccessFul()
{
string fileName = "c:\\Temp\\UnitTest3.txt";
FileInfo fileInfo = new FileInfo(fileName);
FileStream fileStream = null;
try
{
fileStream = File.Create(Path.Combine(fileName));
}
finally
{
if (fileStream != null)
fileStream.Dispose();
}
bool success = FileActions.DeleteFile(fileInfo);
Assert.IsTrue(success);
}

How to get the text sent to console output in an event or method

I need to capture the event when my application is trying to write something on console.
Console.WriteLine("Any text");
Is it possible to get the text sent to console output in an event or method?
One approach would be to create a new stream override, as shown in this article:
http://mel-green.com/2010/01/progressstream/
Then, you would need to set this as the stream that Console writes to, e.g.
MemoryStream ms = new MemoryStream();
ProgressStream progressStream = new ProgressStream(ms);
Console.SetOut(new StreamWriter(progressStream));
Then use the events of the progress stream to see when it is written to.
This may be helpful to you:
using System;
using System.IO;
namespace nsStreams
{
public class Redirect
{
static public void Main ()
{
FileStream ostrm;
StreamWriter writer;
TextWriter oldOut = Console.Out;
try
{
ostrm = new FileStream ("./Target.txt", FileMode.OpenOrCreate, FileAccess.Write);
writer = new StreamWriter (ostrm);
}
catch (Exception e)
{
Console.WriteLine (e.Message);
return;
}
Console.SetOut (writer);
Console.SetOut (oldOut);
writer.Close();
ostrm.Close();
Console.WriteLine ("Done");
}
}
}
Here is an example I used to make a thread-safe listener for Console content that we're "printing" into an observable collection that a WPF Element is bound to.
Create a custom TextWriter class so you can hook into the process:
public class CustomTextWriter : TextWriter
{
private readonly StringBuilder lineBuffer = new();
public event EventHandler<StringEventArgs>? LogModelReadyToAdd;
public override Encoding Encoding => Encoding.UTF8;
public override void Write(char value)
{
// This is the inner-most write, as it is down to a single character
if (value is '\r' or '\n')
{
if (lineBuffer.Length > 0)
{
LogModelReadyToAdd?.Invoke(
this,
new(lineBuffer.ToString()));
lineBuffer.Clear();
}
return;
}
lineBuffer.Append(value);
}
}
With a quick string event args object:
public class StringEventArgs : EventArgs
{
public StringEventArgs()
{
}
public StringEventArgs(string #string)
{
String = #string;
}
public string? String { get; init; }
}
And in my main window (where the context is for me to bind, I have this in my OnInitialized):
CustomTextWriter writer = new();
writer.LogModelReadyToAdd += async (_, args) =>
{
if (Application.Current.CheckAccess())
{
TheContext.StepLog?.Add(new() { Log = args.String, });
return;
}
await Application.Current.Dispatcher.BeginInvoke(
DispatcherPriority.Background,
new Action(() => TheContext.StepLog?.Add(new() { Log = args.String, })));
};
Console.SetOut(writer);

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