sort array list of structure (key value) C#

Question

I have an Array list of a custom class which is essentially has two attributes Key and Value

public class myClass
{
    public key { get; set; }
    public value { get; set; }
}

ArrayList myList = new ArrayList();
// myList is a list of myClass

How can I sort myList by Key?

I've been doing this below in the past the problem is i can't use it anymore because it doesn't handle the case of duplicate keys, i cant have two of same keys in dictionary.

// pseudo code
loop and add to dictionary (Key, Value)  
sort dictionary  
Dictionary<string, string> sortedTypes = myList.
    OrderBy(i => i.Key).ToDictionary(i => i.Key, i => i.Value);

edit: I need it sorted by key first then value as second criteria

Anon. · Accepted Answer · 2011-02-22 02:29:58Z

6

First of all: Don't use ArrayList. Use the generic type List<myClass> instead.

Then, just use the List.Sort method, passing an appropriate delegate to use for the comparison.

list.Sort((x, y)=>x.key.CompareTo(y.key))

answered Feb 22, 2011 at 2:29

Anon.

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Kirk Woll · Accepted Answer · 2011-02-22 02:38:07Z

3

If myList were a List<myClass> instead, then you could just do:

myList = myList.OrderBy(x => x.key).ToList();

You could also use the Sort method on List itself, but that requires some awkward hoops to use the comparator.

Incidentally, class names and public fields/properties should be capitalized (MyClass and Key respectively.)

edited Feb 22, 2011 at 2:38

answered Feb 22, 2011 at 2:29

Kirk Woll

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Comments

Scott M. · Accepted Answer · 2011-02-22 02:49:59Z

2

Why aren't you using a Dictionary<key, value>? it lets you just grab anything by the key. You can also access the keys independently via methods of the class as well. If you use a built in type like string, the sorting comparator is already there for you.

edit: the above is wrong for this situation. but I am leaving it to show that Dictionary does not work here.

Another suggestion: you could use something like SortedList<Key, List<Value>> so your list will always be sorted. The only caveat is that insertion time is greater than that of a regular list.

edited Feb 22, 2011 at 2:49

answered Feb 22, 2011 at 2:25

Scott M.

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2 Comments

Kirk Woll Over a year ago

The OP stated

I've been doing this below in the past the problem is i can't use it anymore because it doesn't handle the case of duplicate keys, i cant have two of same keys in dictionary.

Scott M. Over a year ago

aha. i'm blind. Well a "dictionary" by normal definition doesn't allow duplicate keys. He is looking more for something like a hash map, but with a list at each location.

Ben Sewards · Accepted Answer · 2012-10-10 15:32:51Z

2

If you are required to start with a List, you can easily convert to a dictionary and then sort by value:

objectList.OrderBy(i => i.Value).ToDictionary(i => i.Key, i => i.Value)

answered Oct 10, 2012 at 15:32

Ben Sewards

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Comments

JAiro · Accepted Answer · 2011-02-22 02:28:50Z

1

You could convert the array to List with Array.AsList(array) and the use linq with something like

list.OrderBy(x=> x.Key)

:)

answered Feb 22, 2011 at 2:28

JAiro

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Comments

Dave · Accepted Answer · 2012-09-18 14:30:28Z

Here an example:

 public class EventAlarm
{
    List<EventProperty> propertyList = null;

    public EventAlarm()
    {
       propertyList = new List<EventProperty>();
    }

    public addProperty(string key, string value)
    {
        propertyList.Add(new EventProperty(key, value));
    }

    public sortProperty()
    {
        propertyList.Sort((x, y)=>x.key.CompareTo(y.key)) 
    }

}


private class EventProperty
{
    #region  Properties

    private string key;
    private string value;
    private bool isPropertyValid;

    public string Key
    {
        get { return key; }
        set { key = value; }
    }

    public string Value
    {
      get { return this.value; }
      set { this.value = value; }
    }

    public bool IsPropertyValid
    {
      get { return isPropertyValid; }
      set { isPropertyValid = value; }
    }

    #endregion  Properties

    #region Constructor

    public EventProperty(string key, string value)
    {
        this.Key = key;
        this.Value = Value;
    }

    #endregion Constructor

    #region Methods

    public void PropertyValidation()
    {
        // Here write Code ...
    }

    #endregion Methods
}

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