Breaking Strings into chars that are in upper case

Question

I\'m making a method to read a whole class code and do some stuff with it.

What I want to do is get the name of the method, and make a String with it.

Someth

Answer 1

You can use a regular expression to split the name into the various words, and then capitalize the first one:

public static void main(String[] args) {
    String input = "removeProduct";

    //split into words
    String[] words = input.split("(?=[A-Z])");

    words[0] = capitalizeFirstLetter(words[0]);

    //join
    StringBuilder builder = new StringBuilder();
    for ( String s : words ) {
        builder.append(s).append(" ");
    }

    System.out.println(builder.toString());

}

private static String capitalizeFirstLetter(String in) {
    return in.substring(0, 1).toUpperCase() + in.substring(1);
}

Note that this needs better corner case handling, such as not appending a space at the end and handling 1-char words.

Edit: I meant to explain the regex. The regular expression (?=[A-Z]) is a zero-width assertion (positive lookahead) matching a position where the next character is between 'A' and 'Z'.

Answer 2

@MrWiggles is right. Just one more way to do this without being fancy :)

import java.util.StringTokenizer;

public class StringUtil {

    public static String captilizeFirstLetter(String token) {
        return Character.toUpperCase(token.charAt(0)) + token.substring(1);
    }

    public static String convert(String str) {
        final StringTokenizer st = new StringTokenizer(str,
                "A B C D E F G H I J K L M N O P Q R S T U V W X Y Z", true);
        final StringBuilder sb = new StringBuilder();
        String token;
        if (st.hasMoreTokens()) {
            token = st.nextToken();
            sb.append(StringUtil.captilizeFirstLetter(token) + " ");
        }

        while (st.hasMoreTokens()) {
            token = st.nextToken();
            if (st.hasMoreTokens()) {
                token = token + st.nextToken();
            }

            sb.append(StringUtil.captilizeFirstLetter(token) + " ");
        }
        return sb.toString().trim();
    }

    public static void main(String[] args) throws Exception {

        String words = StringUtil.convert("helloWorldHowAreYou");
        System.out.println(words);
    }
}

Answer 3

Don't bother reinvent the wheel, use the method in commons-lang

String input = "methodName";
String[] words = StringUtils.splitByCharacterTypeCamelCase(methodName);
String humanised = StringUtils.join(words, ' ');

Answer 4

You can do this in 2 steps:

1 - Make the first letter of the string uppercase.

2 - Insert an space before an uppercase letter which is preceded by a lowercase letter.

For step 1 you can use a function and for step 2 you can use String.replaceAll method:

String str = "removeProduct";
str = capitalizeFirst(str);
str = str.replaceAll("(?<=[^A-Z])([A-Z])"," $1");

static String capitalizeFirst(String input) {
      return input.substring(0, 1).toUpperCase() + input.substring(1);
}

Code In Action

Answer 5

public String convertMethodName(String methodName) {
    StringBuilder sb = new StringBuilder().append(Character.toUpperCase(methodName.charAt(0)));
    for (int i = 1; i < methodName.length(); i++) {
        char c = methodName.charAt(i);
        if (Character.isUpperCase(c)) {
            sb.append(' ');
        }
        sb.append(c);
    }
    return sb.toString();
}

Handling it this way may give you some finer control in case you want to add in functionality later for other situations (multiple caps in a row, etc.). Basically, for each character, it just checks to see if it's within the bounds of capital letters (character codes 65-90, inclusive), and if so, adds a space to the buffer before the word begins.

EDIT: Using Character.isUpperCase()