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How to sort a list of lists

Sneha Kashyap
Greenhorn

Joined: May 06, 2009
Posts: 22
Hi,
I am trying to sort a list of lists


the data in the list is something like this
{[def,ghi,xml],
[abc,ghi,cde],
[cat,ghi,der]}
I want the data to be
{[abc,ghi,cde],
[cat,ghi,der],
[def,ghi,xml],}
I am not able to use Collections.sort(listOfLists)
Any help is greatly appreciated.
Thanks in advance.
Christophe Verré
Sheriff

Joined: Nov 24, 2005
Posts: 14687
    
  16

You have to tell the Collections how you want this list to be sorted. What about making a Comparator<List<String>> ?


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Sneha Kashyap
Greenhorn

Joined: May 06, 2009
Posts: 22
Thanks
Hey can you please help me with some sample code.
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 37936
    
  22
Sneha Kashyap wrote:Thanks
Hey can you please help me with some sample code.
No. We believe people learn better if they show us what ideas they have first.

Write whatever you have: if you have no code, write down in small words how to sort your list of lists. Note this text with the lines is full of small words.
Istvan Kovacs
Ranch Hand

Joined: May 06, 2010
Posts: 100
Since you want to sort the lists based on the 1st String they contain (at least, this is my understanding), have a class implement Comparator<List<String>> as Christophe has suggested, in its method extract the 1st item from each list, and (since Strings are Comparable) just invoke Be sure to handle the case when either of the lists is empty.
Pseudo-code:
Rob Spoor
Sheriff

Joined: Oct 27, 2005
Posts: 19651
    
  18

Given two List<String> objects the main question is indeed how they should be compared. The following is an often used algorithm (pseudo code):


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