How I can control a ArrayList for duplicate value?

Question

I have a arraylist with string(codes) and I want to control whether a string is duplicate in this arraylist. if the string is duplicate i want a other code to the arraylist.

my code:

private void btn_Create_Click(object sender, EventArgs e)
{
    ArrayList list = new ArrayList();

    try
    {
        list = DoDeserialize(); 
    }
    catch (Exception ex)
    {
        lbl_status.Text = ex.Message; 
    }

    string code = GetCode(7);

    code = "2 - " + code;

    int test = list.IndexOf(code); 

    txt_Code.Text = code;
    lbl_status.Text = "Code wurde erstellt";


    list.Add(code);

    DoSerialize(list);
}

Could you use List<string>? A better choice. Just saying.. — nawfal
– nawfal, Commented Jul 15, 2013 at 12:20
You can check if the content is already available using perhaps, List#contains() in Java , not sure of C# ! — AllTooSir
– AllTooSir, Commented Jul 15, 2013 at 12:21

Scott · Accepted Answer · 2013-07-15 12:28:40Z

3

Add this in place of your list.add(code);. This method checks whether the item is already in the array list.

if(!list.Contains(code))
{
    // The code does not already exist in the list, so add it
    list.add(code);
} else {
    // The code already exists, do something here.
}

See here for more information about the List<T>.Contains() method.

edited Jul 15, 2013 at 12:28

answered Jul 15, 2013 at 12:22

Scott

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2 Comments

Mike Perrenoud Over a year ago

And there is probably an else here too right? The OP stated they wanted to add a different code if it's a duplicate -- or at least I think that's what they meant. :D

Scott Over a year ago

@MichaelPerrenoud Good point. I have added the else branch, and comments to make this clear.

Alex Barac · Accepted Answer · 2013-07-15 12:33:47Z

0

You can also use the LINQ method Distinct to remove any duplicates after you have populated your list.

answered Jul 15, 2013 at 12:33

Alex Barac

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