Match strings with regular expression in ignore case

I need to match strings in my array which are not starting with "KB" string. I have tried this

String[] ar = {"KB_aaa","KB_BBB", "K_CCC", "!KBD", "kb_EEE", "FFFF"};
Pattern p = Pattern.compile("[^(^KB)].*");

for(String str : ar)
{
    Matc开发者_Python百科her m = p.matcher(str);
    if(m.matches())
         System.out.println(str);
}

But it still not matches "K_CCC". Thanks

I wouldn't use RegEx for everything.

for(String str : ar)
{
    if(!str.toUpperCase().startsWith("KB"))
        System.out.println(str);
}

From the way your question is worded, I'm not entirely sure whether you want the match to be case insensitive or not. This regex:

(?i)[^k][^b].*

uses the flag (?i) to turn off case sensitivity, and should do want you want.

    String[] ar = {"KB_aaa","KB_BBB", "K_CCC", "!KBD", "kb_EEE", "FFFF"};
    Pattern p = Pattern.compile("^KB.*", Pattern.CASE_INSENSITIVE);

    for(String str : ar)
    {
        Matcher m = p.matcher(str);
        if(!m.matches())
             System.out.println(str);
    }

A regex that matches anything not starting with KB is:

^(?!KB).*

To do it in java:

if (str.matches("^(?!KB).*$")) ...

You shouldn't use RegExes everywhere. Just create a simple check:

for (String str : ar)
{
    if (!str.toLowerCase().startsWith("kb"))
        System.out.println(str);
}

And I think, that this method is even better in performace (not that performance is needed in your case):

public static boolean accept(String name)
{
    if (name.length() < 2) return true;
    String sub = name.substring(0, 2);
    return !sub.equalsIgnoreCase("KB");
}

What do others thing of this second way of working?

Use the regex (?i)^(?!kb).* for case insensitive matches. It will avoid KB234 Kb*432, kB2343 and kb23445.

Here is the code snippet that can help for the ignore case understanding with String.matches function, for further details please use this [link][1]

String stringToSearch = "Four score and seven years ago our fathers ...";

// this won't work because the pattern is in upper-case
System.out.println("Try 1: " + stringToSearch.matches(".*SEVEN.*"));

// the magic (?i:X) syntax makes this search case-insensitive, so it returns true
System.out.println("Try 2: " + stringToSearch.matches("(?i:.*SEVEN.*)"));

Try 1: false
Try 2: true

[1]: http://alvinalexander.com/blog/post/java/java-how-case-insensitive-search-string-matches-method/#:~:text=Solution%3A%20Use%20the%20String%20matches,must%20match%20the%20entire%20string.)