How to do case insensitive RegEx in Java?

Question

I have a private method that I use for finding drug name using RegEx. The code is as following,

private boolean containsExactDrugName(String testString, String drugName) {

    int begin = -1;
    int end = -1;

    Matcher m = Pattern.compile("\\b(?:" + drugName + ")\\b|\\S+", Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE).matcher(testString);
    ArrayList<String> results = new ArrayList<>();

    while (m.find()) {
        results.add(m.group());
    }

    boolean found = results.contains(drugName);
    return found;
}

It should take a drug name and finds exact match inside the text String. That means if the drug name is insuline and the the String text is The patient is taking insulineee for the treatment of diabetes, it will break. It will need the exact match of The patient is taking insuline for the treatment of diabetes.

However, I also need case insensitive matches and if the text is The patient is taking Insuline for the treatment of diabetes or The patient is taking INSULINE for the treatment of diabetes, the method should return true as well.

I put the Pattern.CASE_INSENSITIVE inside the code, however, it doesn't work. How to write it properly ?

I do not understand why you need `\S+`. Look [here](https://ideone.com/9kZJNu), is the result expected? — Wiktor Stribiżew, Oct 24 '16 at 11:22
That `|\\S+` looks very suspicious. It says "Or match any sequence of non-space characters". — khelwood, Oct 24 '16 at 11:27
If `insulineee` is inside the text, the return type needs to be `false` — Chaklader, Oct 24 '16 at 11:27
Please check https://ideone.com/ekbweD where the check for a whole word is performed, and if it is in the string, it is split with whitespace. — Wiktor Stribiżew, Oct 24 '16 at 11:47
Or if you just need true or false, see https://ideone.com/MxH730 — Wiktor Stribiżew, Oct 24 '16 at 11:52

score 5 · Answer 1 · answered Oct 24 '16 at 11:27

5

@Chaklader

Pattern.CASE_INSENSITIVE is the method I'm known to. It should work. for ASCII only case-insensitive matching

Pattern p = Pattern.compile("YOUR_REGEX GOES HERE", Pattern.CASE_INSENSITIVE);

or for Unicode case-folding matching

Pattern p = Pattern.compile("YOUR_REGEX GOES HERE", Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE);

answered Oct 24 '16 at 11:27

Amjad Zahid

71
9

check if you are using non ASCII characters. – Amjad Zahid Oct 24 '16 at 11:27
1

This is the same what I use and still not working. I will report back after doing some more testing. – Chaklader Oct 24 '16 at 11:29
do a test of given method on a sample program and check for results. If Ok, then find problem in your actual program. – Amjad Zahid Oct 24 '16 at 11:39

How to do case insensitive RegEx in Java?

1 Answers1