Matching numbers patterns using regular expressions (regex)

Need your kind help in matching some numbers patterns using regex.
I have thousands of 10-digit numbers in the following patterns and need to extract them according to their patterns.

Note - I don't need spaces in between.

Pattern 1:
Number: 3527 432 432
Let's consider the above number as
ABCD XYZ XYZ pattern

Pattern 2:
Number:
3527 89 89 89
ABCD XY XY XY

Pattern 3:
Number:
35 35 35 8745
XY XY XY ABCD

Pattern 4:
5432 888 999
ABCD XXX YYY

Pattern 5:
5432 8888 99
ABCD XXXX YY

Pattern 6
5432 33 44 22
ABCD XX YY ZZ

Any kind of help in any manner is much appreciated.

I am a complete beginner in regex and know basic things.

For patterns like
5432 8888 99

I am using regex like
\d\d\d\d8888\d\d

and then manually find the matching numbers from the list by changing 8888 to other digits like 1111.

To check for same symbols, you can use backreferences.

In short, regex like (.)\1 will match two same symbols in a row, and (.)(.)\1\2 will match occurrences like abab.

Here expressions for your cases:

1. \d{4}(\d{3})\1
2. \d{4}(\d{2})\1{2}
3. (\d{2})\1{2}\d{4}
4. \d{4}(\d)\1{2}(\d)\2{2}
5. \d{4}(\d)\1{3}(\d)\2
6. \d{4}(\d)\1(\d)\2(\d)\3

Explanation for the firs one:

• \d{4} matches any for digits,
• (\d{3}) matches any three digits, and captures them into group #1,
• \1 matches exact content of the group #1.

I hope that based on this explanation and general description how backreferences work, others expressions should be pretty clear.

Demo for the first one here.

The simplest approach would be to write a pattern for each of the formats.
And then, append them with the | character.

Pattern 1 and 4.

\d{4} \d{3} \d{3}

Pattern 2 and 6.

\d{4} \d{2} \d{2} \d{2}

Pattern 3.

\d{2} \d{2} \d{2} \d{4}

Pattern 5.

\d{4} \d{4} \d{2}

The final pattern would be,

\d{4} \d{3} \d{3}|\d{4} \d{2} \d{2} \d{2}|\d{2} \d{2} \d{2} \d{4}|\d{4} \d{4} \d{2}

Or, simplified to,

\d{4}(?: \d{3}){2}|\d{4}(?: \d{2}){3}|(?:\d{2} ){3}\d{4}|(?:\d{4} ){2}\d{2}

You could then use the Pattern and Matcher classes to obtain each value.
Subsequently, use the String#replace method to remove the spaces.

This presumes they are within a text, and are each delimited by some other character.

I wouldn't rely on this pattern, if the values are sequential and not delimited.

String string = "3527 432 432, 3527 89 89 89, 35 35 35 8745, 5432 888 999, 5432 8888 99, 5432 33 44 22";
Pattern pattern = Pattern.compile("\\d{4}(?: \\d{3}){2}|\\d{4}(?: \\d{2}){3}|(?:\\d{2} ){3}\\d{4}|(?:\\d{4} ){2}\\d{2}");
Matcher matcher = pattern.matcher(string);
while (matcher.find())
    System.out.printf("%-20s = %s%n", matcher.group(), matcher.group().replace(" ", ""));

Output

3527 432 432         = 3527432432
3527 89 89 89        = 3527898989
35 35 35 8745        = 3535358745
5432 888 999         = 5432888999
5432 8888 99         = 5432888899
5432 33 44 22        = 5432334422

Here is a link to the Wikipedia article on regular expressions.
Wikipedia – Regular expression.