How to create regex pattern for Number Patterns like AAAABBB and AAABBCC

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How to create regex pattern for Number Patterns like AAAABBB and AAABBCC. Number matched in the first group should not be considered in the 2nd and later groups.


Here:
A = [0-9] Any number between 0 to 9
B = [0-9] Any number between 0 to 9 excluding A
C = [0-9] Any number between 0 to 9 excluding A and B

For example : 5555333, 7777999, 2225588, 1113377 etc. I want to find such numbers from the bigger number range using java regex.

pattern-matching regex java
1 Answers

I believe this does what you want. It captures the desired digit, followed by 0 or more of the same digit, not followed by any previous digit using back references in the negative look ahead assertions.

String pat = "(\\d)\\1*(?:(\\d)\\2*(?!\\1)){1,2}";
long[] data = {112233, 123333, 888777555, 999666, 222111222,222222, 111122221, 11223344,44442222,444455522, 522212121};
for (long i : data) {
    String s = Long.toString(i);
    System.out.printf("%12s - %s%n", s, s.matches(pat) ? "Valid" : "Invalid");
}

Prints

      112233 - Valid
      123333 - Valid
   888777555 - Valid
      999666 - Valid
   222111222 - Invalid
      222222 - Valid
   111122221 - Invalid
    11223344 - Invalid
    44442222 - Valid
   444455522 - Valid
   522212121 - Invalid
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