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Java Dictionary Search

Posted on 2007-11-28
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Hi,

I am trying to develop a piece of Java to search a dictionary for words that best-fit a charachter input stream. I found a piece of code on ee that I have included with this post that looks like it may be a fairly close fit. The problem I'm having with is that it finds things when it shouldn't!

Say the dictionary file only contained the following words:
absonant
absonous
absorb
absorbable
absorbate
absorbed
absorbefacient
absorbency
absorbent
absorber
absorbing
absorption

If the input stream was "ABSO", it should put all of those words into an array as possible options.
It would get the next character "R" and drop "absoNant" and  "absoNous", next character "B" and drop "absorPtion".
Eventually having to make a desicion on a "best-fit" word.
Problem is that i'd like it to come back with a best-fit word rather than nothing - like taking a guess.
If the next character after "B" was "X" making "ABSORBX" - it's not in the list, so perhaps getting the next character allows the guess to be made - next character after "X" is "D", "ABSORBXD" - it makes a decision to selec "ABSORBED" as a best-fit.
 
First problem I have with the code below is that
- enter "ABSO" - it returns not found (correct I think - the word is not in the dictionary, but words begin with it??)
- enter "ABSOX" - it returns found (I don't think its supposed to - word not in dictionary and no words begin with it.)

If anyone can help me overcome these problems, i'd very much appreciate the help!!

Thanks in advance!

Cheers,

Phil.

public class Wordsearch {
 
 
    public static void main(String args[]) throws IOException {
 
         ArrayList words = loadFile("dictionary.txt"); // Load the word in arrayList
 
         Collections.sort(words); //sort ArrayList required for binarySearch
 
         BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
         while (true) {
            System.out.print("Enter Word (q to quit) ");
            System.out.print("\n");
            String option = stdin.readLine();
 
            if (option.equalsIgnoreCase("q")) System.exit(-1);
            else {
 
               if (Arrays.binarySearch(words.toArray(),option.toLowerCase())== -1)
                   System.out.println("Word is not found in dictionary.");
               else
                   System.out.println("Word Found");
            }
 
         }
 
    }
 
   private static ArrayList loadFile(String fileName) throws IOException{
        String word;
 
        File file  = new File(fileName);
        BufferedReader bfreader = new BufferedReader(new InputStreamReader(new FileInputStream(file)));
        ArrayList wordList = new ArrayList();
        while ((word=bfreader.readLine()) != null){
         wordList.add(word.toLowerCase());
 
        }
 
        return wordList;
 
   }
}

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Question by:phil8258
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11 Comments
 
LVL 86

Expert Comment

by:CEHJ
ID: 20365040
That code is using exact (case-insensitive) matching. You probably need something like fuzzy matching algos
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 20365049
0
 
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Expert Comment

by:CEHJ
ID: 20365055
Java Lucene uses Levenshtein
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LVL 26

Expert Comment

by:ksivananth
ID: 20365084
>>enter "ABSOX" - it returns found (I don't think its supposed to - word not in dictionary and no words begin with it.)
>>

try below,

if (Arrays.binarySearch(words.toArray(),option.toLowerCase()) < 0)

the binary serach returns < 0 if it doesn't found but it is not -1 always!
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 20365266
Change

>>Arrays.binarySearch(words.toArray()

to

Collections.binarySearch(words

as there's no reason to convert
0
 

Author Comment

by:phil8258
ID: 20367714
Ok, thanks. Those changes work pretty well.

The second part of the problem is now that I want to store a list of words
So that if you search the dictionary for the input string "absorbe", you get a list containing:
absorbed, absorbefacient, absorbency, absorbent, absorber

Anyone any idea how this could be done?
A snippet of code would be really helpful to get me kick started.

Cheers.
 
0
 
LVL 86

Accepted Solution

by:
CEHJ earned 2000 total points
ID: 20367850
Just need to do something like

String target = "absorbe";
ArrayList found = new ArrayList();
for(int i = 0;i < wordList.size();i++) {
    String word = (String)wordList.get(i).toLowerCase();
    if (word.substring(target) > -1) {
        found.add(word);
    }
}

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Author Comment

by:phil8258
ID: 20368044
Thanks for that prompt.
line 5 is having a little difficulty.
"The method substring(int) in the type String is not applicable for the arguments (String)"
any idea how to fix it?
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 20368069
Sorry!


if (word.indexOf(target) > -1) {
        found.add(word);
}

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Author Comment

by:phil8258
ID: 20368118
sorted. thanks :O)
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 20368327
:-)
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