Search string in arraylist advanced (Java)

Question

I have used the .equals method to search for a String in an ArrayList, but the user has to write the exact name of the String. Is there a way to show the String that matches the user input containing ? If you for example search for 'Djang' and the String you are trying to find is 'Django'.

• MadProgrammer: You could use a regular expression or something like String#contains
• Sleiman Jneidi: what do you mean by "name of the String"?

Answer 1

You should check out the Levenshtein Distance. It measures how far away a string is from another string. There is even a Java implementation in Wikibooks.

Then, it's a matter of sorting and finding the minimum.

list.stream()
 .sort(Comparator.comparing(
 s -> LevenshteinDistance.computeLevenshteinDistance(s, input))
 .findFirst();

From there, it's also possible to filter to add an upper bound on the acceptable distance to prevent all inputs from returning a result.

list.stream()
 .sort(Comparator.comparing(
 s -> LevenshteinDistance.computeLevenshteinDistance(s, input))
 .filter(s -> LevenshteinDistance.computeLevenshteinDistance(s, input) < limit)
 .findFirst();

• John: The LevenshteinDistance is a good point. But I think the implements is not that good. by using LevenshteinDistance.computeLevenshteinDistance directly in the comparing, this costly method would be called many more times. Maybe this can be done by .filter first, or use a map to store string and the metric.

Answer 2

try the String.contains() method

public boolean contains(CharSequence s) Returns true if and only if this string contains the specified sequence of char values.

Parameters: s - the sequence to search for

Returns: true if this string contains s, false otherwise

Throws: NullPointerException - if s is null

Since: 1.5

For example:

String myString = "Django"
public boolean stringCatcher(String userInput) {
 return myString.contains(userInput);
}

then passing Djang to stringCatcher() would result in a true value being returned.

• Casper Nørsø: That actually works pretty well. Guess it was kind of a noob question too, i feel like i should have known this or at least be able to search me to the answer:-). Thanks for the quick answer though!