Need to change lowercase_underscore string to camelCase

Question

I Need to change String : underbar + lowercase = uppercase.(and the opposite)

my_name -> myName

Is there any library or something to help this out?

Answer 1

You can use the CaseFormat class's LOWER_UNDERSCORE from google Guava :

CaseFormat.LOWER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, "my_name")

Answer 2

I suggest a custom solution

    Pattern p = Pattern.compile("_(.)");
    Matcher m = p.matcher("my_name");
    StringBuffer sb = new StringBuffer();
    while (m.find()) {
        m.appendReplacement(sb, m.group(1).toUpperCase());
    }
    m.appendTail(sb);
    System.out.println(sb.toString());

output

myName

Answer 3

CaseFormat is an utility class in Google Guava for converting between case conventions.

Answer 4

Another solution is to use StringTokenizer:

    String value = "id_app";
    StringTokenizer toekn = new StringTokenizer(value,"_");
    StringBuilder str = new StringBuilder(toekn.nextToken());
    while (toekn.hasMoreTokens()) {
        String s = toekn.nextToken();
        str.append(Character.toUpperCase(s.charAt(0))).append(s.substring(1));
    }
    System.out.println(str.toString());

Answer 5

Check this code, I have verified it.

        String str = new String("my_name");

        for(int i=0;i<str.length()-1;i++){
            if(str.charAt(i)=='_' && (int) str.charAt(i+1)>=97 && (int) str.charAt(i+1)<=122){
              str=str.replace(str.substring(i, i+2),""+(char)((int) str.charAt(i+1)-32));
            }
        }
        System.out.println(str);

Answer 6

String s="My_name";
        int i=s.indexOf('_');       
        s=s.replaceFirst(Character.toString(s.charAt(i+1)),Character.toString(Character.toUpperCase(s.charAt(i+1))));
        s=s.replaceAll("_","");

Answer 7

String s="srinivas";

s=s.replaceFirst(Character.toString(s.charAt(0)), 
                 Character.toString(Character.toUpperCase(s.charAt(0))));

//s Value is "Srinivas" now

Answer 8

You can replace lower case character following underscore with uppercase using appendReplacement

The appendReplacement and appendTail methods can be used in tandem in order to collect the result into an existing string buffer

    String text = "my_name_is";
    Matcher m = Pattern.compile("([_][a-z])").matcher(text);
    StringBuffer sb = new StringBuffer();
    while (m.find()) {
        m.appendReplacement(sb, m.group().substring(1).toUpperCase());
    }
    m.appendTail(sb);