How to sort Strings considering the digits inside them?

Question

I have some codes looking like the one of following:

aaa_bbb_d2_aa
aaa_bbb_d3_aa
aaa_bbb_d11_aa
eee_b2b_c2_ac

In general they should be sorted as strings, however in case of “aaa_bbb_d3_aa” vs. “aaa_bbb_d11_aa” the former should come first in contrast to simple string sorting.

The numerical part that is important for sorting always resides after either the “_d” or “_c” substring and always is followed by “_aa” or by “_ac” ending the string.

What is an efficient sorting algorithm in Java or SQL?

So for your example, it would sort aaa before eee? Or do you want to sort specifically on the _d3 vs _d11 part? — Adam, May 29 '15 at 15:58
@anarinsky Do you have any ideas of your own that you would like to share? — Chetan Kinger, May 29 '15 at 16:01
Take a look at [this question](http://stackoverflow.com/q/1262239/335858). — Sergey Kalinichenko, May 29 '15 at 16:03
try to extract number from string, compare numbers and voilà, extracting number from a string should be called when your first method cant decide which string should be first — itwasntme, May 29 '15 at 16:04
@WhyCry, yes aaa should be sorted before eee, only strings differ by numerical parts after _d or or _c should be sorted by number — Alex, May 29 '15 at 16:04
What trouble did you run into when you implemented your code? Can you give details? — Bohemian, May 29 '15 at 16:10

score 1 · Answer 1 · answered May 29 '15 at 16:08

Collections.sort(yourListOfString, (String a, String b) ->
{
    int comparison = Integer.valueOf(a.split("_")[2].replaceAll("[dc]", "")).compareTo(Integer.parseInt(b.split("_")[2].replaceAll("[dc]", "")));

    return comparison == 0
             ? a.split("_")[3].compareTo(b.split("_")[3])
             : comparison;
});

(I assume all your strings are in a list)

score 0 · Accepted Answer · answered Jun 26 '15 at 23:04

0

I ended up with NaturalOrderComparator.java: https://github.com/paour/natorder . Thanks @dasblinkenlight for the useful comment

answered Jun 26 '15 at 23:04

Alex

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How to sort Strings considering the digits inside them?

2 Answers2