I'm trying to sort an ArrayList of String.
Given:
{A,C,AA,B,CC,BB}
Arraylist.Sort gives:
{A,AA,B,BB,C,CC}
What I need is:
{A,B,C,AA,BB,CC}
5 Answers
ArrayList list = new ArrayList {"A","C","AA","B","CC","BB"};
var sorted = list.Cast<string>()
.OrderBy(str => str.Length)
.ThenBy(str => str);
//LinqPad specific print call
sorted.Dump();
prints:
A
B
C
AA
BB
CC
2 Comments
Servy
Just note that this doesn't modify the ArrayList, it creates a new sequence of the values from that collection. (It may be acceptable, it's just important to be aware of that.)
Ilya Ivanov
yes, sure, good note. Another note that even if you modify
list after sorted variable has been declared, but before actually called - than it would contain new element. sorted query is being executed in deferred mannerIt's easier to do this with Linq as so:
string [] list = { "A","C","AA","B","CC","BB"};
var sorted = list.OrderBy(x=>x.Length).ThenBy(x=>x);
Note that the OrderBy method returns a new list. If you want to modify the original, then you need to re-assign it as so:
list = list.OrderBy(x=>x.Length).ThenBy(x=>x).ToArray();
Comments
This is kind of old school but, I went the IComparer Interface . . .
public class SortAlphabetLength : System.Collections.IComparer
{
public int Compare(Object x, Object y)
{
if (x.ToString().Length == y.ToString().Length)
return string.Compare(x.ToString(), y.ToString());
else if (x.ToString().Length > y.ToString().Length)
return 1;
else
return -1;
}
}
and then test it . . .
class Program
{
static void Main(string[] args)
{
ArrayList values = new ArrayList()
{
"A","AA","B","BB","C","CC"
};
SortAlphabetLength alphaLen = new SortAlphabetLength();
values.Sort(alphaLen);
foreach (string itm in values)
Console.WriteLine(itm);
}
}
output:
A
B
C
AA
BB
CC
7 Comments
Servy
Now put a
null value in that collection and see what happens.
rbtLong
I'm sorry I didn't see that in the question. I'm just trying to answer the question. Thanks for pointing that out though.
Servy
If you're writing code to only display the sorted values of that one example than you may as well just print out A, B C, ... It's example input, not the only input he'll ever have to put into it.
rbtLong
Thanks for nitpicking. Wise, Sir.
Servy
Yeah, robust code that works is overrated; it's much better to use code that's longer, more complex, is harder to understand, and occasionally crashes when there is a sensible course of action.
|
I would suggest using the ToArray() method (or just using a List<string> instad of an ArrayList) to take advantage of the OrderBy and ThenBy functions. It would look something like this:
list = list.OrderBy(/*Order it by length*/).ThenBy(/*Order alphabetically*/);
Comments
You could create an IComparable class taking in two Strings and sort them as follows:
if (a.Length == b.Length)
return String.Compare(a, b);
return a.Length.CompareTo(b.Length);
You may also want to handle null cases.
List<string>?