Comparing current string to text file Java

Question

I want to know if there is a way to compare a String to a text file to get the best possible answer. Example: We have a this in text file:

BANANA
BANTER
APPLE
BASKET
BASEBALL

and the current String is: B.N... (with the dots being the unknown characters). Is there a way to instantly get an array or hashmap with the possible letters (so A, T and E) out of the text file?

What I think I should do: I have managed to get every line of the text file in a arraylist. I should compare the current String to the possible answers in the arraylist and get every character in that word on the place of the dots and put it in a new arraylist.

Thanks in advance.

Sounds like a school project, what is your attempted code so far? — voice
– voice, Commented Jan 18, 2016 at 16:03
Is this like a spellchecking algorithm or is it an autocomplete algorithm? Reading up on the Aho-Corasick algorithm might be a step in the right direction. — Jim W
– Jim W, Commented Jan 18, 2016 at 16:07
@JimW it is an autocomplete algorithm. And thanks I will check it out. — Jesse Vlietveld
– Jesse Vlietveld, Commented Jan 18, 2016 at 16:08

EPresident · Accepted Answer · 2016-01-18 16:27:01Z

2

You could try to use regular expressions. Your current String "B.N..." must be translated into a Pattern, which you will match with the other words present in the text file. You can find a tutorial on regular expressions here.

Here's a little example:

public class RegexPlayground {
    public static void main(String[] args){
        Pattern pattern=Pattern.compile("B.N...");
        String word="BANANA";
        Matcher matcher = pattern.matcher(word);
        if(matcher.find()){
            System.out.println("Found matching word \""+word+"\"");
        }
        word="BASKET";
        matcher = pattern.matcher(word);
        if(matcher.find()){
            System.out.println("Found matching word \""+word+"\"");
        }else{
            System.out.println("No match on word \""+word+"\"");
        }
    }
}

Output:

Found matching word "BANANA"

No match on word "BASKET"

So the overall logic of the program should be like this:

String regex = getRedex(); // This is your B.N...
Pattern pattern = Pattern.compile(regex);
List<String> words=readFromFile(); // The list of words in the text file
for(String word: words){
    Matcher matcher = pattern.matcher(word);
    if(matcher.find()){
        // Match found
        // do what you need to do here
    }else{
        // Same here
    }
}

answered Jan 18, 2016 at 16:27

EPresident

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1 Comment

Jesse Vlietveld Over a year ago

Thanks for the answer. Worked perfectly!

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