CODEWITHSUNDEEP
javaregex
Learner
Learner

Reputation: 21405

Regular expression is giving wrong result

I am writing a simple regular expression program using the expression:

uid=swg2*([C]?[1247]\d{6})

Initially I tried to get a valid input string for this expression using the online regex tool and got a valid example string as uid=swg2C1\dddddd.

I also tried with uid=swg2C1\\123456 in my Java program but getting same issue.

Now if I use this in my Java program then it is not working as expected:

public static void main(String[] args) {
    String input = "uid=swg2C1\\dddddd"; // Tried with "uid=swg2C1\\123456", same issue
    if (Pattern.compile("uid=swg2*([C]?[1247]\\d{6})").matcher(input).find()) {
        System.out.println("valid input");
    } else {
        System.out.println("invalid input");
    }
}

If I run this program I am getting message as invalid input. But my string is valid input as per the online tool. Please help me what is wrong with my input data.

Upvotes: 0

Views: 201

Answers (1)

Sweeper
Sweeper

Reputation: 271460

You did not escape your backslashes!

uid=swg2*([C]?[1247]\\d{6})
                    ^^
             These should be escaped!

In Java code, if you did not escape them, the two backslashes in Java code will become one \ in regex. This means that the engine will treat the string like this:

uid=swg2*([C]?[1247]\d{6})

\d means digits, so the engine thinks you are trying to match 6 digits!

So, remember to escape them by adding one more \ before each \:

"uid=swg2*([C]?[1247]\\\\d{6})"

Upvotes: 2

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