How can I sort strings with numbers in them naturally?

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Sort on a string that may contain a number

I'm implementing a custom sorting algorithm for a homework assignment, and I want it to sort strings with numbers attached at the end in proper order... As it is right now, "Book1" is coming after "Book10".

I'm using String.compareTo() to get the ordering, but I don't see a version of compareTo() that lets me choose any special kind of ordering.

Thanks.

You need to implement a custom comparator which breaks up your string into parts which you expect to be compared as if they were fields. — Peter Lawrey, Nov 15 '12 at 17:00

score 0 · Answer 1 · answered Nov 15 '12 at 17:04

0

You have to write your own implementation of Comparator that:

Splits the leading string from the trailing number.
Compares the leading strings for equality.
If equal, compares the trailing numbers for equality.

answered Nov 15 '12 at 17:04

Gilbert Le Blanc

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Why compare only for equality? – Rohit Jain Nov 15 '12 at 17:06
Because if the strings aren't equal, you can return from the comparator with a +1 or a -1. – Gilbert Le Blanc Nov 15 '12 at 17:12
That's why I said. You don't just need to compare for equality. But `<` and `>` also. Well this is really not so much of a concern. I just pointed out. :) – Rohit Jain Nov 15 '12 at 17:16
True. You would use the String compareTo method. For the number, you'd have to make at least two tests (< and >). – Gilbert Le Blanc Nov 15 '12 at 17:20

How can I sort strings with numbers in them naturally?

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