Super fast autocomplete using binary search in a sorted file (300,000 lines)

Question

In my Android app, I want to have an autocomplete input field. The number of elements will be around 300,000. The best solution seems to be to put the elements in a file (on sdcard), one element per line, each line will have the same number of characters so that I can search for a specific line number. If the user enters something in the text box, I would have a binary search (via RandomAccessFile) file and show the sentences.

I want autocomplete to be super fast (ideally up to 100 ms, but I think it's impossible), what optimizations can I do?

Update 1: I will convert user input to lowercase English characters (az) with spaces. Thus, "A / b" will be converted to "a b", and then a search will be performed.

Uodate 2: Now I realized that I need an extra thing - look for source substrings.

Answer 1

What you are looking for is called TRIE

http://forums.sun.com/thread.jspa?threadID=5295936

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Answer 2

SQLite?
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Answer 3

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Answer 4

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Answer 5

http://en.wikipedia.org/wiki/Binary_search_algorithm

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Answer 10

Old thread, but THIS WHAT NEEDS : Stringsearch library

I used it for my Wordlist Pro application for Android, and it is very fast.

Answer 11

I could also do something like this (below is a pre-processed file):

aa - line 1
ab - line 17
.
.
zz - line 299819 

If the user enters something starting with aa, I would read lines 1 through 17 and search them sequentially