First char to upper case

Question

Possible Duplicate:
How to upper case every first letter of word in a string?
Most efficient way to make the first character of a String lower case?

I want to convert the first letter of a string to upper case. I am attempting to use replaceFirst() as described in JavaDocs, but I have no idea what is meant by regular expression.

Here is the code I have tried so far:

public static String cap1stChar(String userIdea)
{
    String betterIdea, userIdeaUC;
    char char1;
    userIdeaUC = userIdea.toUpperCase();
    char1 = userIdeaUC.charAt(0);
    betterIdea = userIdea.replaceFirst(char1); 
    return betterIdea;
}//end cap1stChar

The compiler error is that the argument lists differ in lengths. I presume that is because the regex is missing, however I don't know what that is exactly.

`String s = "this is a String"; s= s.substring(0,1).toUpperCase() + s.substring(1);` — Luiggi Mendoza, Jul 13 '12 at 05:56
You might want to check http://docs.oracle.com/javase/tutorial/essential/regex/ — Prakhar Mohan Srivastava, Jul 13 '12 at 05:56
This is the way: http://stackoverflow.com/questions/1892765/capitalize-first-char-of-each-word-in-a-string-java — Luxspes, Jul 13 '12 at 05:56

Jon Egeland · Accepted Answer · 2012-07-13T16:49:53.377

74

Regular Expressions (abbreviated "regex" or "reg-ex") is a string that defines a search pattern.

What replaceFirst() does is it uses the regular expression provided in the parameters and replaces the first result from the search with whatever you pass in as the other parameter.

What you want to do is convert the string to an array using the String class' charAt() method, and then use Character.toUpperCase() to change the character to upper case (obviously). Your code would look like this:

char first = Character.toUpperCase(userIdea.charAt(0));
betterIdea = first + userIdea.substring(1);

Or, if you feel comfortable with more complex, one-lined java code:

betterIdea = Character.toUpperCase(userIdea.charAt(0)) + userIdea.substring(1);

Both of these do the same thing, which is converting the first character of userIdea to an upper case character.

edited Jul 13 '12 at 16:49

answered Jul 13 '12 at 06:04

Jon Egeland

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`userIdea.toCharArray()[0]` is an expensive way of doing `userIdea.charAt(0)` – Peter Lawrey Jul 13 '12 at 08:16
@PeterLawrey I don't know how I forgot about that. Thanks. – Jon Egeland Jul 13 '12 at 16:48
StringBuilder class is great companion suppose name is String than code => if(name.length()>0){ StringBuilder stringBuilder = new StringBuilder(name); if(stringBuilder.length()==1){ name= String.valueOf(Character.toUpperCase(stringBuilder.charAt(0))); }else{ name= String.valueOf(Character.toUpperCase(stringBuilder.charAt(0)))+stringBuilder.substring(1); } } – Rajesh Prasad Yadav Nov 22 '18 at 15:55

score 41 · Answer 2 · answered Jul 13 '12 at 06:00

41

Or you can do

s = Character.toUpperCase(s.charAt(0)) + s.substring(1);

answered Jul 13 '12 at 06:00

Peter Lawrey

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Does not work for strings shorter than two characters. – Thilo Jul 13 '12 at 06:03
2

@Thilo: Yes, it works for strings of length 1. – Keppil Jul 13 '12 at 06:27
It doesn't work for strings of length 0 – Peter Lawrey Jul 13 '12 at 08:14
2

Why should anyone want to get an uppercase equivalent of the first character of a null string? – Mob Jul 13 '12 at 15:04
4

Maybe those who don't want their programs to crash due to unexpected null strings ;-) – dokaspar Aug 06 '12 at 11:39
2

@Dominik Do you mean "unexpected empty strings" ? A `null` is a different situation. – Peter Lawrey Aug 06 '12 at 11:44

score 6 · Answer 3 · answered Jul 13 '12 at 05:58

6

public static String cap1stChar(String userIdea)
{
    char[] stringArray = userIdea.toCharArray();
    stringArray[0] = Character.toUpperCase(stringArray[0]);
    return userIdea = new String(stringArray);
}

answered Jul 13 '12 at 05:58

Pramod Kumar

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score 4 · Answer 4 · answered Jul 13 '12 at 06:38

Comilation error is due arguments are not properly provided, replaceFirst accepts regx as initial arg. [a-z]{1} will match string of simple alpha characters of length 1.

Try this.

betterIdea = userIdea.replaceFirst("[a-z]{1}", userIdea.substring(0,1).toUpperCase())

score 4 · Answer 5 · answered Jul 13 '12 at 10:20

4

String toCamelCase(String string) {
    StringBuffer sb = new StringBuffer(string);
    sb.replace(0, 1, string.substring(0, 1).toUpperCase());
    return sb.toString();

}

answered Jul 13 '12 at 10:20

Pranav Kevadiya

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score 3 · Answer 6 · answered Jul 13 '12 at 05:56

3

userIdeaUC = userIdea.substring(0, 1).toUpperCase() + userIdea.length() > 1 ? userIdea.substring(1) : "";

or

userIdeaUC = userIdea.substring(0, 1).toUpperCase();
if(userIdea.length() > 1)
   userIdeaUC += userIdea.substring(1);

answered Jul 13 '12 at 05:56

juergen d

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Might want to remove the ternary expression for readability to Matt B. – trevor-e Jul 13 '12 at 05:59

score 0 · Answer 7 · answered Jul 13 '12 at 06:08

For completeness, if you wanted to use replaceFirst, try this:

public static String cap1stChar(String userIdea)
{
  String betterIdea = userIdea;
  if (userIdea.length() > 0)
  {
    String first = userIdea.substring(0,1);
    betterIdea = userIdea.replaceFirst(first, first.toUpperCase());
  }
  return betterIdea;
}//end cap1stChar

First char to upper case

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