How to identify date from a string in Java

Question

Recently I am being challenged by quite an "easy" problem. Suppose that there is sentences (saved in a String), and I need to find out if there is any date in this String. The challenges is that the date can be in a lot of different formats. Some examples are shown in the list:

• June 12, 1956
• London, 21st October 2014
• 13 October 1999
• 01/11/2003

Worth mentioning that these are contained in one string. So as an example it can be like:

String s = "This event took place on 13 October 1999.";

My question in this case would be how can I detect that there is a date in this string. My first approach was to search for the word "event", and then try to localize the date. But with more and more possible formats of the date this solution is not very beautiful. The second solution that I tried is to create a list for months and search. This had good results but still misses the cases when the date is expressed all in digits.

One solution which I have not tried till now is to design regular expressions and try to find a match in the string. Not sure how much this solution might decrease the performance.

What could be a good solution that I should probably consider? Did anybody face a similar problem before and what solutions did you find?

One thing is for sure that there are no time, so the only interesting part is the date.

Answer 1

Using the natty.joestelmach.com library

Natty is a natural language date parser written in Java. Given a date expression, natty will apply standard language recognition and translation techniques to produce a list of corresponding dates with optional parse and syntax information.

import com.joestelmach.natty.*;

List<Date> dates =new Parser().parse("Start date 11/30/2013 , end date Friday, Sept. 7, 2013").get(0).getDates();
        System.out.println(dates.get(0));
        System.out.println(dates.get(1));

//output:
//Sat Nov 30 11:14:30 BDT 2013
//Sat Sep 07 11:14:30 BDT 2013

Answer 2

You are after Named Entity Recognition. I'd start with Stanford NLP. The 7 class model includes date, but the online demo struggles and misses the "13". :(

Natty mentioned above gives a better answer.