I need a Regex expression that will stop anything that is not 3 (or more) letter word?

Question

In my code I want anything that isn't a three (or more) letter word to go into the while loop and anything else to continue into the code. I am not that confident with Regex and would like help on how to fix it.

    while (!(word.matches("(a-z){3,}")))
    {
        System.out.println("You have not entered in a valid word (it has to be at least 3 letters long).");

        System.out.println();

        System.out.print("Please enter a word of your choice: ");
        word = keyboard.nextLine();

    }

N.B. This is for homework

`(a-z)` should be `[A-z]`, `(a-z)` will only match `a-z` but you can just say `\w{0,3}` this will match all collections of letter characters with a length of 3 or less I know regex is super confusing at first but you will get it, I used regexr.com a lot while I was still learning — Robbie Milejczak, Nov 28 '17 at 20:58
@RobbieMilejczak Thanks, and for words with 3 or more letters would you do \w{3,} ? — red_star_12, Nov 28 '17 at 21:00
yep, `\w{3,}` also that should be `\w{1,3}` I had a brainfart — Robbie Milejczak, Nov 28 '17 at 21:01
@JohnKane I also want to check if it is a word and my teacher prefers if I do it in one Regex condition — red_star_12, Nov 28 '17 at 21:02
@red_star_12 I let you see below the answer explaining it ;) — azro, Nov 28 '17 at 21:08

azro · Accepted Answer · 2017-11-28T21:05:59.033

You need to use [a-z] whiich means a char between a and z, rather than (a-z) which means match exactly "a-z"

You'd better \w class that represents word-character = [a-zA-Z0-9_]
\w = a letter between a and z OR bewtween A and Z OR between 0 and 9, or a _

==> regex demo

while (!word.matches("\\w{3,}")) {  // don't match more than 3
   //
}

// -- OR --

while (word.matches("\\w{0,3}")) {  // match between 0 and 3 is also correct
   //
}

I need a Regex expression that will stop anything that is not 3 (or more) letter word?

1 Answers1