CODEWITHSUNDEEP
javaregex
user3788818
user3788818

Reputation: 21

What is the correct regex to match uppercase letter for only first letter in words

Now my program use this pattern .*[A-Z].* to match every word that has an uppercase letter. But my problem is, I need a pattern that can identify a word with an uppercase only on the beginning of word.

Example Input for my program now:-

My name is Johan and I am from langKawi.

Output Matched: My Johan I langKawi.

But using my pattern a word like langKawi where the uppercase is not at the beginning of a word it still matched.

Can anyone help me with the pattern where it match a word that has uppercase for the first letter only and my text/input only consist alphabetical characters without number and symbols. Thank you.

Upvotes: 2

Views: 7896

Answers (2)

willeM_ Van Onsem
willeM_ Van Onsem

Reputation: 476659

That's why they invented \b:

\b[A-Z][A-Za-z]*\b

\b acts as a word boundary: it matches spaces (and other delimiters) or the begin and end of a string.

Example to capture all parts:

import java.util.regex.*;

public class HelloWorld{

     public static void main(String []args){
        Pattern p = Pattern.compile("\\b([A-Z][a-z]*)\\b");
        Matcher m = p.matcher("My name is Johan and I am from langKawi.");
        while(m.find()) {
            System.out.println(m.group(1));
        }
     }
}

You can test the code here.

Upvotes: 2

nickb
nickb

Reputation: 59699

Use a word boundary to match just before a word starts, then the word, then another word boundary:

\b[A-Z]\w*\b

That, in Java, looks like this:

Pattern p = Pattern.compile("\\b([A-Z]\\w*)\\b");

String s = "My name is Johan and I am from langKawi.";
Matcher matcher = p.matcher(s);

while(matcher.find()){
    System.out.println(matcher.group(1));
}

This outputs:

My
Johan
I

Upvotes: 4

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