Java search at text a list of variables

Question

First of all, sorry for my bad english.

I googled for this question, but had no good info about it.

I own a text with about 3 million words. My need is to do a search for words in this text, I have a list of all those words and I need to find the same in this text, I would like the help of companions for a good idea how to do this with a result of meaningful time.

Thanks for the help.

Best regard´s.

Will you need to search for words several times or just once? — Tudor
– Tudor, Commented Dec 9, 2011 at 12:19
Do you need to find all the instances of a specific word, or just decide if the word is in the text? — tobier
– tobier, Commented Dec 9, 2011 at 12:25
Sorry for the less of data in the post, I need to search each word all the time in the input text. I´m reading this input text via .txt loaded with BufferedReader. Thanks in advance. — digoferra
– digoferra, Commented Dec 9, 2011 at 12:56

David · Accepted Answer · 2011-12-09 12:18:16Z

4

Have a look at lucene: http://lucene.apache.org/java/docs/index.html

answered Dec 9, 2011 at 12:18

David

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3 Comments

digoferra Over a year ago

I already used Lucene with Zend Framework at php, but for one search at one text, could I be used to several searchs inside a text loaded with BufferedReader? Thanks.

David Over a year ago

Sure its possible: to gain an idea have a look at this example javatechniques.com/blog/lucene-in-memory-text-search-example

digoferra Over a year ago

Thanks again, I will test this example with a .txt file as entrance and an ArrayList with the words to match.

M S · Accepted Answer · 2011-12-09 12:20:34Z

1

It would be very inneficient to search the text each time from the text file.

If memory is not a constrain you can add each word in Arraylist and do binary search by

Collections.binarySearch() API

answered Dec 9, 2011 at 12:20

M S

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4 Comments

digoferra Over a year ago

That´s a great idea too, load each word to the coolection and search by binary, but I need to convert the words to binary to match the words in the list, don´t? Thanks.

Tudor Over a year ago

@Rodrigo Ferrari: binary search has nothing to do with binary format. It is an efficient recursive algorithm that partitions the collection and searches on increasingly smaller sub-collections. It finds an element in O(log(N)) instead of O(N), but requires the collection to be sorted.

M S Over a year ago

@Rodrigo Ferrari. Not needed. U can use the normal string comparisons. As Tudor said its the most efficient way to search sorted item.

digoferra Over a year ago

Thanks, will try these usage and the Lucene idea.

narek.gevorgyan · Accepted Answer · 2011-12-09 12:20:38Z

1

Check these libraries, http://johannburkard.de/software/stringsearch/

answered Dec 9, 2011 at 12:20

narek.gevorgyan

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1 Comment

digoferra Over a year ago

Great one, it will be studed during the software development. Thanks!

Tudor · Accepted Answer · 2011-12-09 12:21:18Z

1

If you need to search for the words only once, then I don't think you can do better than just a linear search over the text.

If you need to do several searches, then you will need to index your text and maybe use something like Lucene.

answered Dec 9, 2011 at 12:21

Tudor

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1 Comment

digoferra Over a year ago

Yeah, I need to search over the text several times, 50.000 times is the small search at a text with 3 million words. Thanks.

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