CODEWITHSUNDEEP
javaregex
Anonhacer2397
Anonhacer2397

Reputation: 1

How do I check if a string is of a certain pattern without splitting it up?

So this is the problem. Can someone tell me how a regex pattern might look like?

Write a program that determines if the input string matches the following format:

Format: PRODUCT_ID.PRODUCT_CATEGORY-LOCATOR_TYPE[LOCATOR_LOT]

  • PRODUCT_ID = always starts with # followed by 3 zeros, followed by a numeric value that can be 1-7 digits, in the range 1-9999999
  • PRODUCT_CATEGORY = 1-4 uppercase alphabetic characters
  • LOCATOR_TYPE = a single uppercase X, Y or Z character
  • LOCATOR_LOT = 1-2 numeric digits, in the range 1-99

All other format characters are the literal characters

Return true if it matches and false otherwise.

This is the function declaration:

public boolean checkPattern(String s){    
}

I tried splitting the string and then checking every character but it got very complicated.

Here's what I've got so far for a regex:

String regex = "#000^([1-9]|[1-9][0-9]|[1-9][0-9][0-9]|[1-9][0-9][0-9][0-9]|[1-9][0-9][0-9][0-9][0-9]|[1-9][0-9][0-9]|[1-9][0-9][0-9])$";

This is something I started with but its so long and complicated and not even complete (only checks the product id) that I dont think I am on the right track here

Upvotes: 0

Views: 172

Answers (2)

Khaled Adrani
Khaled Adrani

Reputation: 171

I think you should try to determine the pattern of each element and then merge between them. I was able to identify every part but I did not understand the last one:

All other format characters are the literal characters.

Anyway, I hope this will help you out. Read the comments included in the code.

public boolean checkPattern(String s){

     if(s.matches("#000[1-9]{1,7}.[A-Z]{1,4}-([X-Z])\\[[1-9]{1,2}\\]")) return true;
          else return false; 

      // #000[1-9]{1,7} ==> matches PRODUCT_ID

      //. ==> to simply match the point

      // [A-Z]{1,4} ==> PRODUCT_CATEGORY

      //- ==> to simply match this symbol

      // ([X-Z]) ==> LOCATOR_TYPE

      // \\[ Use the double slash here so the [ symbol becomes recognized 

      // [1-9]{1,2} ==> LOCATOR_LOT

      // \\]

      //  String s="#000123.ABC-X[99]"; this is a test example I used.

}

While working with Regular expressions, you have to read well what is requested from you as well as the predefined regex operators and tools.

Upvotes: 0

Andrew
Andrew

Reputation: 776

Here's a working regex:

#000[1-9]\d{0,6}\.[A-Z]{1,4}\-[XYZ]\[[1-9]\d?\]

And here's a breakdown:

#000    # match the literal characters, #000
[1-9]   # any digit 1 to 9 (to ensure there are no preceding zeroes)
\d      # any digit character; equivalent to [0-9]
{0,6}   # perform the preceding match (\d) anywhere from 0 to 6 times
        #    (0,6 instead of 1,7 because we already matched the first digit above)

\.      # match a dot character. Must be escaped with a backslash \ as
        #    the unescaped dot will match *anything* in regex otherwise.

[A-Z]   # any uppercase alphabetic character.
{1,4}   # will repeat the preceding match anywhere from 1 to 4 times.

\-      # match a hyphen character. escaping is optional here.

[XYZ]   # any of X, Y, or Z.

\[      # a literal [ character. Must be escaped.

[1-9]   # matches 1 to 9
\d      # any digit; equivalent to [0-9]
?       # Makes the preceding match optional. Equivalent to {0,1}

\]      # a literal ] character. Must be escaped.

Other notes:

A really nice tool that can help you understand regex better is the website RegExr.com

Upvotes: 1

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