To take a generic `List&lt;T&gt;` vs a bound `List&lt;int&gt;` you need to make the method generic as well.  This is done by adding a generic parameter to the method much in the way you add it to a type.  

Try the following

    void Export&lt;T&gt;(List&lt;T&gt; data, params string[] parameters) {
     ...
    }

You need to make the method generic as well:

    void Export&lt;T&gt;(List&lt;T&gt; data, params string[] parameters){
    
    }



    public static  List&lt;T&gt; pesquisa_lista&lt;T&gt;(string campo, string valor, List&lt;T&gt; lista)  
    {
       return new List&lt;T&gt;();
    }

How can I get the next friday with the [Joda-Time][1] API.

The [`LocalDate`][2] of today is `today`. It looks to me you have to decide whever you are before or after the friday of the current week. See this method:

	private LocalDate calcNextFriday(LocalDate d) {
		LocalDate friday = d.dayOfWeek().setCopy(5);
		if (d.isBefore(friday)) {
			return d.dayOfWeek().setCopy(5);
		} else {
			return d.plusWeeks(1).dayOfWeek().setCopy(5);
		}
	}

Is it possible to do it shorter or with a oneliner?

&lt;strike&gt;PS: Please don&#39;t advise me using JDKs date/time stuff. Joda-Time is a much better API.&lt;/strike&gt;

Java 8 introduces [java.time][3] package ([Tutorial][4]) which is even better.


  [1]: http://www.joda.org/joda-time/
  [2]: http://www.joda.org/joda-time/apidocs/org/joda/time/LocalDate.html
  [3]: https://docs.oracle.com/javase/8/docs/api/java/time/package-summary.html
  [4]: https://docs.oracle.com/javase/tutorial/datetime/

Time: How to get the next friday?

Let&#39;s say I have a list of arbitrary length, L:

    L = list(range(1000))

What is the best way to split that list into groups of `n`?  This is the best structure that I have been able to come up with, and for some reason it does not feel like it is the best way of accomplishing the task:

    n = 25
    for i in range(0, len(L), n):
        chunk = L[i:i+25]

Is there a built-in to do this I&#39;m missing?

**Edit:** Early answers are reworking my for loop into a listcomp, which is not the idea; you&#39;re basically giving me my exact answer back in a different form.  I&#39;m seeing if there&#39;s an alternate means to accomplish this, like a hypothetical `.split` on lists or something.  I also do use this as a generator in some code that I wrote last night:

    def split_list(L, n):
        assert type(L) is list, &quot;L is not a list&quot;
        for i in range(0, len(L), n):
            yield L[i:i+n]

Alternative way to split a list into groups of n

How can I use a `List&lt;T&gt;` as a parameter on a method, I try this syntax :


    void Export(List&lt;T&gt; data, params string[] parameters){
    
    }

I got compilation error: 

&gt; The type or namespace name &#39;T&#39; could not be found (are you missing a using directive or an assembly reference?)

Generic List&lt;T&gt; as parameter on method

How can I use a <code>List&#x3C;T></code> as a parameter on a method, I try this syntax :
<pre><code class="hljs language-csharp">void Export(List&#x3C;T> data, params string[] parameters){

}
</code></pre>
I got compilation error:
> The type or namespace name 'T' could not be found (are you missing a using directive or an assembly reference?)

I have a `Dictionary&lt;string, string&gt;`.

I need to look within that dictionary to see if a value exists based on input from somewhere else and if it exists remove it.

ContainsValue just says true/false and not the index or key of that item.

Help!

Thanks

**EDIT:** Just found this - what do you think?

    var key = (from k in dic where string.Compare(k.Value, &quot;two&quot;, true) ==
    0 select k.Key).FirstOrDefault();

**EDIT 2:** I also just knocked this up which might work

    foreach (KeyValuePair&lt;string, string&gt; kvp in myDic)
    {
        if (myList.Any(x =&gt; x.Id == kvp.Value))
            myDic.Remove(kvp.Key);
    }



Remove Item in Dictionary based on Value

My colleagues are using Visual Studio 2002 and uses the C++ MFC. I am developing in C #. 

It has not been any problems before, but now questioning our customers if we really should develop in different environments. My colleagues think (of course) that I should move to C++ MFC. I think that they can use .NET instead of MFC. 

Is there any point to learn the MFC? It feels a bit outmoded, or am I wrong? What are the arguments against and for .NET compared with MFC?

**Edit:**

We are developing process systems and assistance applications for the nuclear industry. The main application is an emulator that emulates an old computer system and uses C++/MFC. It is very time critical, maybe the core should it still be in native C++. But the GUI to the emulator and all surrounding applications are not particularly critical.

And is there any real reason that you should replace the existing MFC application?

C++ MFC vs .NET?

I stitched together from code I found in internet myself `WH_KEYBOARD_LL` helper class:

Put the following code to some of your utils libs, let it be **YourUtils.cs**:

    using System;
    using System.Diagnostics;
    using System.Runtime.InteropServices;
    using System.Runtime.CompilerServices;
    using System.Windows.Input;

    namespace MYCOMPANYHERE.WPF.KeyboardHelper
    {
        public class KeyboardListener : IDisposable
        {
            private static IntPtr hookId = IntPtr.Zero;

            [MethodImpl(MethodImplOptions.NoInlining)]
            private IntPtr HookCallback(
                int nCode, IntPtr wParam, IntPtr lParam)
            {
                try
                {
                    return HookCallbackInner(nCode, wParam, lParam);
                }
                catch
                {
                    Console.WriteLine(&quot;There was some error somewhere...&quot;);
                }
                return InterceptKeys.CallNextHookEx(hookId, nCode, wParam, lParam);
            }

            private IntPtr HookCallbackInner(int nCode, IntPtr wParam, IntPtr lParam)
            {
                if (nCode &gt;= 0)
                {
                    if (wParam == (IntPtr)InterceptKeys.WM_KEYDOWN)
                    {
                        int vkCode = Marshal.ReadInt32(lParam);

                        if (KeyDown != null)
                            KeyDown(this, new RawKeyEventArgs(vkCode, false));
                    }
                    else if (wParam == (IntPtr)InterceptKeys.WM_KEYUP)
                    {
                        int vkCode = Marshal.ReadInt32(lParam);

                        if (KeyUp != null)
                            KeyUp(this, new RawKeyEventArgs(vkCode, false));
                    }
                }
                return InterceptKeys.CallNextHookEx(hookId, nCode, wParam, lParam);
            }

            public event RawKeyEventHandler KeyDown;
            public event RawKeyEventHandler KeyUp;

            public KeyboardListener()
            {
                hookId = InterceptKeys.SetHook((InterceptKeys.LowLevelKeyboardProc)HookCallback);
            }

            ~KeyboardListener()
            {
                Dispose();
            }

            #region IDisposable Members

            public void Dispose()
            {
                InterceptKeys.UnhookWindowsHookEx(hookId);
            }

            #endregion
        }

        internal static class InterceptKeys
        {
            public delegate IntPtr LowLevelKeyboardProc(
                int nCode, IntPtr wParam, IntPtr lParam);

            public static int WH_KEYBOARD_LL = 13;
            public static int WM_KEYDOWN = 0x0100;
            public static int WM_KEYUP = 0x0101;

            public static IntPtr SetHook(LowLevelKeyboardProc proc)
            {
                using (Process curProcess = Process.GetCurrentProcess())
                using (ProcessModule curModule = curProcess.MainModule)
                {
                    return SetWindowsHookEx(WH_KEYBOARD_LL, proc,
                        GetModuleHandle(curModule.ModuleName), 0);
                }
            }

            [DllImport(&quot;user32.dll&quot;, CharSet = CharSet.Auto, SetLastError = true)]
            public static extern IntPtr SetWindowsHookEx(int idHook,
                LowLevelKeyboardProc lpfn, IntPtr hMod, uint dwThreadId);

            [DllImport(&quot;user32.dll&quot;, CharSet = CharSet.Auto, SetLastError = true)]
            [return: MarshalAs(UnmanagedType.Bool)]
            public static extern bool UnhookWindowsHookEx(IntPtr hhk);

            [DllImport(&quot;user32.dll&quot;, CharSet = CharSet.Auto, SetLastError = true)]
            public static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode,
                IntPtr wParam, IntPtr lParam);

            [DllImport(&quot;kernel32.dll&quot;, CharSet = CharSet.Auto, SetLastError = true)]
            public static extern IntPtr GetModuleHandle(string lpModuleName);
        }

        public class RawKeyEventArgs : EventArgs
        {
            public int VKCode;
            public Key Key;
            public bool IsSysKey;

            public RawKeyEventArgs(int VKCode, bool isSysKey)
            {
                this.VKCode = VKCode;
                this.IsSysKey = isSysKey;
                this.Key = System.Windows.Input.KeyInterop.KeyFromVirtualKey(VKCode);
            }
        }

        public delegate void RawKeyEventHandler(object sender, RawKeyEventArgs args);
    }

Which I use like this:

**App.xaml**:

    &lt;Application ...
        Startup=&quot;Application_Startup&quot;
        Exit=&quot;Application_Exit&quot;&gt;
        ...

**App.xaml.cs**:

    public partial class App : Application
    {
        KeyboardListener KListener = new KeyboardListener();

        private void Application_Startup(object sender, StartupEventArgs e)
        {
            KListener.KeyDown += new RawKeyEventHandler(KListener_KeyDown);
        }

        void KListener_KeyDown(object sender, RawKeyEventArgs args)
        {
            Console.WriteLine(args.Key.ToString());
            // I tried writing the data in file here also, to make sure the problem is not in Console.WriteLine
        }

        private void Application_Exit(object sender, ExitEventArgs e)
        {
            KListener.Dispose();
        }
    }

The problem is that it **stops working after hitting keys a while**. No error is raised what so ever, I just don&#39;t get anything to output after a while. I can&#39;t find a solid pattern when it stops working.

Reproducing this problem is quiet simple, hit some keys like a mad man, usually outside the window.

I suspect there is some evil *threading problem* behind, anyone got idea how to keep this working?

----------

What I tried already:

1. Replacing `return HookCallbackInner(nCode, wParam, lParam);` with something simple.
2. Replacing it with asynchronous call, trying to put Sleep 5000ms (etc).

Asynchronous call didn&#39;t make it work any better, it seems stop always when user keeps single letter down for a while.

Using global keyboard hook (WH_KEYBOARD_LL) in WPF / C#

I have an object of the type `IEnumerable&lt;KeyValuePair&lt;T,U&gt;&gt; keyValueList`, I am using 

     var getResult= keyValueList.SingleOrDefault();
     if(getResult==/*default */)
     {
     }
     else
     {
     } 

How can I check whether `getResult` is the default, in case I can&#39;t find the correct element?

I can&#39;t check whether it is `null` or not, because `KeyValuePair` is a struct. 


The default for KeyValuePair

Consider this class:

    public class Content
    {      
       public virtual bool IsCheckedOut {get; private set;}
       public virtual void CheckOut()
       {
          IsCheckedOut = true;
       }

       public virtual void CheckIn()
       {
          //Do Nothing for now as demonstrating false positive test.
       }
    }

The Checkin method is intentionally empty.  Now i have a few test methods to verify the status of calling each method.

    [TestMethod]
    public void CheckOutSetsCheckedOutStatusToTrue()
    {
        Content c = new Content();    
        c.CheckOut();
        Assert.AreEqual(true, c.IsCheckedOut); //Test works as expected
    }
    
    [TestMethod]
    public void CheckInSetsCheckedOutStatusToFalse()
    {
        Content c = new Content();
        c.CheckIn();
        Assert.AreEqual(false, c.IsCheckedOut); //Test does not work as expected
    }

The 2nd test passes for the wrong reasons.  So how can i use mocking (moq) to verify that CheckIn is setting the IsCheckedOut property?

Thanks.

**EDIT**

To clarify: I have a method called CheckIn() whose job it is to set the IsCheckedOut status to false.  

You will see in my test code above that the Test will return false even if i do not set the property value to false;  This is expected, nothing wrong here.

I think my question specifically is How can i verify that the CheckIn() method has set the IsCheckedOut property to false?  This is what I would call behavioral verification.  

I believe some of the comments suggested doing something which amounts to state verification? If so I don&#39;t believe there is any value in mocking this part at all when we can simply use:

    Content c = new Content();    
    c.CheckIn();    
    Assert.AreEqual(false, c.IsCheckedOut); //State verification

Of course I may be wrong, so please help me clarify these concepts :)

Moq - How to verify that a property value is set via the setter

Is there a clean method of mocking a class with generic parameters?  Say I have to mock a class `Foo&lt;T&gt;` which I need to pass into a method that expects a `Foo&lt;Bar&gt;`.  I can do the following easily enough:

    Foo mockFoo = mock(Foo.class);
    when(mockFoo.getValue).thenReturn(new Bar());
   
Assuming `getValue()` returns the generic type `T`.  But that&#39;s going to have kittens when I later pass it into a method expecting `Foo&lt;Bar&gt;`.  Is casting the only means of doing this?

Using Mockito to mock classes with generic parameters

Recently I noticed that generic constructed types can be open and closed. But I do not understand what they actually mean. Can you give a simple example?

Generics open and closed constructed types

I was wondering if it&#39;s possible to write a function that accepts multiple generic types as follows:

    public int void myfunction(Set&lt;T&gt; a, Set&lt;T&gt; b) {
        return 5;
    }

    Set&lt;Integer&gt; setA = new HashSet&lt;Integer&gt;();
    Set&lt;String&gt; setB = new HashSet&lt;String&gt;();
    int result = myfunction(setA, setB);


Will that work? Does the &lt;T&gt; generic in each parameter mean that each parameter must have the same type T that&#39;s generic?

Java generics: multiple generic parameters?

`HashMap&lt;String, int&gt;` doesn&#39;t seem to work but `HashMap&lt;String, Integer&gt;` does work.
Any ideas why?


java: HashMap&lt;String, int&gt; not working

I want to develop a Generic Extension Method which should arrange the string in alphabetical then by lengthwise ascending order.

I mean

    string[] names = { &quot;Jon&quot;, &quot;Marc&quot;, &quot;Joel&quot;,
                      &quot;Thomas&quot;, &quot;Copsey&quot;,&quot;Konrad&quot;,&quot;Andrew&quot;,&quot;Brian&quot;,&quot;Bill&quot;};
    
    var query = names.OrderBy(a =&gt; a.Length).ThenBy(a =&gt; a);

What is the way to develop Generic Extension Method?

I tried :

    public static class ExtensionOperation
        {
            public static T[] AlphaLengthWise&lt;T&gt;(this T[] names)
            {
                var query = names.OrderBy(a =&gt; a.Length).ThenBy(a =&gt; a);
                return query;
            }
        }

I received :

&gt;Error 1: T does not contain definition for Length
&gt;
&gt;Error 2: can not convert `System.Linq.IOrderedEnumerable` to `T[]`.




How to create a generic extension method?

I have a `System.Drawing.Image` in my program. The file is not on the file system it is being held in memory. I need to create a stream from it. How would I go about doing this?

System.Drawing.Image to stream C#

&lt;pre&gt;&lt;code&gt;Dictionary&amp;lt;string,double&amp;gt; myDict = new Dictionary&lt;string,double&gt;();
//...
foreach (KeyValuePair&amp;lt;string,double&amp;gt; kvp in myDict)
 {
     kvp.Value = Math.Round(kvp.Value, 3);
}&lt;/code&gt;&lt;/pre&gt;
I get an error:
&quot;Property or indexer &#39;System.Collections.Generic.KeyValuePair&lt;string,double&gt;.Value&#39; cannot be assigned to -- it is read only.&quot;&lt;br&gt;
How can I iterate through `myDict` and change values?

How to iterate through Dictionary and change values?

Is there any way to declare a list object of anonymous type. I mean

    List&lt;var&gt; someVariable = new List&lt;var&gt;();
    someVariable.Add(
                 new{Name=&quot;Krishna&quot;, 
                     Phones = new[] {&quot;555-555-5555&quot;, &quot;666-666-6666&quot;}}
                    );

This is because I need to create a collection at runtime.

Declaration of Anonymous types List

```
public object MethodName(ref float y)
{
    // elided
}
```

How do I define a `Func` delegate for this method?

Func delegate with ref variable

Given a datasource like that:

    var c = new Car[]
    {
      new Car{ Color=&quot;Blue&quot;, Price=28000},
      new Car{ Color=&quot;Red&quot;, Price=54000},
      new Car{ Color=&quot;Pink&quot;, Price=9999},
      // ..
    };

How can I find the **index** of the first car satisfying a certain condition with LINQ?

EDIT:

I could think of something like this but it looks horrible:

    int firstItem = someItems.Select((item, index) =&gt; new    
    {    
        ItemName = item.Color,    
        Position = index    
    }).Where(i =&gt; i.ItemName == &quot;purple&quot;)    
      .First()    
      .Position;

Will it be the best to solve this with a plain old loop?


Content Type	Original Author	Original Content on Stackoverflow
Question	Jonathan Escobedo	View Question on Stackoverflow
Solution 1 - C#	JaredPar	View Answer on Stackoverflow
Solution 2 - C#	Fredrik Mörk	View Answer on Stackoverflow
Solution 3 - C#	user3418564	View Answer on Stackoverflow

Generic List<T> as parameter on method

C# Problem Overview

C# Solutions

Solution 1 - C#

Solution 2 - C#

Solution 3 - C#

Alternative way to split a list into groups of n

Time: How to get the next friday?

Attributions