asked on 7/18/2008

How to convert Arraylist to comma delimeted string

I would like to get the values out of an Arraylist and put them into a string .

I have tried following two methods and they both dont work

string[] strings = (string[])al.ToArray(typeof(string)); -- Throws me an error (System.InvalidCastException: At least one element in the source array could not be cast down to the destination array type)

Also tried.

string.Join(delimeter, arrList.ToArray(typeof(string))); -- Throws me a build error.

is there any other way of doing this?

.NET Programming

Last Comment

Wayne Taylor (webtubbs)

7/21/2008

Guy Hengel [angelIII / a3]

7/18/2008

what about this:
http://blog.troyd.net/NET+Code+To+Convert+An+ArrayList+To+A+Comma+Delimited+String+CSV+Or+Other+Character+Delimited+String.aspx

Public Shared Function ArrayListToDelimString(ByVal arrayList As ArrayList, ByVal separator As String) As String 
    Dim stringArrayList As New ArrayList 
    For Each o As Object In arrayList 
      stringArrayList.Add(o.ToString()) 
    Next 
    Return String.Join(separator, stringArrayList.ToArray(GetType(String))) 
  End Function

Open in new window

pratikshahse

7/18/2008

ASKER

This are the two errors that I get

Error      9      The best overloaded method match for 'string.Join(string, string[])' has some invalid arguments

Error      10      Argument '2': cannot convert from 'System.Array' to 'string[]'

ASKER CERTIFIED SOLUTION

Wayne Taylor (webtubbs)

7/19/2008

THIS SOLUTION IS ONLY AVAILABLE TO MEMBERS.

View this solution by signing up for a free trial.

Members can start a 7-Day free trial and enjoy unlimited access to the platform.

See Pricing Options

Start Free Trial

SwatiBhaskar

7/21/2008

The values in arraylist should be string data type, then only you can convert it to string array.

ArrayList ar = new ArrayList();
ar.Add("1");
ar.Add("2");
ar.Add("3");
ar.Add("4");

string[] str = (string[]) ar.ToArray(typeof(string));

return string.Join(",", str ).ToString();

Wayne Taylor (webtubbs)

7/21/2008

>>The values in arraylist should be string data type, then only you can convert it to string array.

That's not entirely correct. They can be any type, as long as they are converted to a string type to be added to the comma delimited string. Obviously this is what was causing the error in the first place, and the asker's question was how to avoid that. For example, what if one item in the arraylist was of an integer type?? The "ToArray" code will fail. Both angelIII's and my code eliminates this problem.

Wayne