Java Regex to find time between two words in a String

Question

I am trying to find the time fields between two specific words in a String. Here is few examples of my inputs

Examples

The Big Cat eats at 3:49 AM and the Big Dog eats  Daily (BBB) , On 12 at 5:00 AM done
The Big Cat eats at 3:49 AM and the Big Dog eats  Daily (BBB) , On 12 at 11:00 PM done

Expected Output

5:00 AM
11:00 PM

RegEx Used

(?<=Dog\s(\w+))((\d):(\d)(\d)\sAM)(?=\sdone)

I dont seem to get it properly. Not sure if the special characters in between are causing the issue. But instead of Alphanumeric, if I use Any character, then all words between my two keywords get captured. Could anyone let me know what am I doing wrong here?

Answer 1

You can use something like this :

    String val="Big Cat eats at 3:49 AM and the Big Dog eats  Daily (BBB) , On 12 at 11:00 AM done";
    String REGEX="(?:Dog[a-zA-Z0-9(),])*([0-9]?[0-9]:[0-9]?[0-9] (AM|PM))(?=\\sdone)";

    Pattern pattern = Pattern.compile(REGEX);
    Matcher matcher = pattern.matcher(val);
    while(matcher.find()){
        System.out.println(matcher.group());
    }

Explanation:

Answer 2

How about

[0-9]?[0-9]:[0-9]?[0-9] AM|PM

Assuming your times are always in the form (x)x:(x)x AM or (x)x:(x)x PM

For clarification:

[0-9]  matches any digit from 0-9
?      matches 0 or 1 occurences
x|y    matches x or y

But, as others have pointed out, if the string is always the same then it is better to use substring etc. With a regex it gets much more complicated than it needs to be.

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Edit: to find it between dog and done do

 Dog.*([0-9]?[0-9]:[0-9]?[0-9] AM|PM).*done

and use \1 to get the matched time or make a substring between Dog and done and use the first regex.

---

Edit2: I added a working example:

public static void main (String[] args) {
    String in = "The Big Cat eats at 3:49 AM and the Big Dog eats  Daily (BBB) , On 12 at 5:00 AM done";
    Pattern pattern = Pattern.compile("Dog.*([0-9]?[0-9]:[0-9]?[0-9] AM|PM).*done");
    Matcher matcher = pattern.matcher(in);

    System.out.println("matching");
    while(matcher.find()) {
        System.out.println(matcher.group(1) + "");
    }
}

Output:

matching
5:00 AM