Searching for string in sorted list in Java, and possibly all strings beginning with part of string

Question

what would be the most effective way to implement search for a string in sorted list of strings in Java?

And what about searching for all the string beginning with part of a string?

Thank you for help.

Answer 1

I think you are looking for Collections#binarySearch for both the requirements.

Answer 2

http://en.wikipedia.org/wiki/Binary_search assuming you are using a java.util.ArrayList or similar non-linked structure.

Answer 3

To search for non-beginning strings (ie 'and' matches 'andrew', 'candy' and 'sand') you will have to do brute force.

For beginning of string, use a BST.

Answer 4

You can just use the Collections.binarySearch() .

Answer 5

A list really isn't the right datastructure for this. First of all binarySearch will in the best case do O(N) for a linkedList - since a list doesn't support random access you don't gain anything by having it sorted.

What you're looking for is a trie . The wiki page describes the advantages and how it works good enough for me not to waste my time trying to trump it. While it doesn't describe the advantages over a sorted LinkedList, just remember that inserting into a sorted LinkedList is O(N) link traversals and O(log n) element comparisons, as is finding an object. The trie is more efficient and still supports all operations you would get from a sorted linked list.

Google finds several results for libraries that support that structure like this one but I haven't used any of them. A trie is still a quite simple data structure (compared to eg AVL trees) so you could implement it yourself quite easily though.

Answer 6

uther.lightbringer rote:

what would be the most effective way to implement search for a string in sorted list of strings in Java?

As other already mentioned, you can use Collections.binarySearch(...) for that. Make sure your list is sorted: otherwise you'll most likely not get the right results.

uther.lightbringer rote:

And what about searching for all the string beginning with part of a string?

Either loop through the list from start to finish and check each word, or create (or grab from the net) a radix tree which can find the words starting with a certain (sub) string much faster than looping over the list of words.