Using regex to match any character except =

Question

I am trying to write a String validation to match any character (regular, digit and special) except =.

Here is what I have written -

    String patternString = "[[^=][\\w\\s\\W]]*";
    Pattern p = Pattern.compile(patternString);
    Matcher m = p.matcher(str);

    if(m.matches())
        System.out.println("matches");
    else
        System.out.println("does not");

But, it matches the input string "2009-09/09 12:23:12.5=" with the pattern.

How can I exclude = (or any other character, for that matter) from the pattern string?

What are you trying to match? (or not)? just [^=]* will match anything but the '=' char. — Guillaume Polet, Mar 19 '12 at 13:17
You cannot nest character classes. `[[]` is simply a character class consisting of the single character `[`. — tripleee, Mar 19 '12 at 13:25

tripleee · Answer 1 · 2015-04-21T04:21:14.787

107

If the only prohibited character is the equals sign, something like [^=]* should work.

[^...] is a negated character class; it matches a single character which is any character except one from the list between the square brackets. * repeats the expression zero or more times.

edited Apr 21 '15 at 04:21

answered Mar 19 '12 at 13:18

tripleee

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How can I make `[^=]*` match `\n`, as well? – Cameron Hudson Jun 11 '21 at 17:36
Not a Java person, but my first search engine match was https://stackoverflow.com/a/30315738/874188 – tripleee Jun 11 '21 at 17:49
Hmm thanks, but my particular use case is search-and-replace in VSCode. – Cameron Hudson Jun 13 '21 at 05:19

score 12 · Answer 2 · answered Mar 19 '12 at 13:20

12

First of all, you don't need a regexp. Simply call contains:

if(str.contains("="))
    System.out.println("does not");
else
    System.out.println("matches");

The correct regexp you're looking for is just

String patternString = "[^=]*";

answered Mar 19 '12 at 13:20

phihag

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This may be very helpful for the original poster. But this answer is very far from the specific text of the question, which leads thousands of others to this page. This alternative has much less value for them. – ctpenrose Mar 11 '19 at 16:55

score 9 · Answer 3 · answered Mar 19 '12 at 13:27

9

If your goal is to not have any = characters in your string, please try the following

String patternString = "[^=]*";

answered Mar 19 '12 at 13:27

Chetter Hummin

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score 3 · Answer 4 · edited Mar 19 '12 at 13:38

3

If you only want to check for occurence of "=" why don't you use the String indexOf() method?

if str.indexOf('=')  //...

edited Mar 19 '12 at 13:38

Josh

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answered Mar 19 '12 at 13:19

moodywoody

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`contains` is shorter, easier to understand, and you don't need to fiddle around with indices. – phihag Mar 19 '12 at 13:21

Using regex to match any character except =

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