Converting a string from snake case to camel case in Java

Question

How can I convert snake case to camel case in Java?

Input: "input_in_snake_case"

Output: "InputInSnakeCase"

That other question is SO not a duplicate of this one. (Although some of the answers are pretty similar :) ) — Andrew Spencer, Nov 09 '17 at 09:03
This question should be reopened, as it clearly states its use case being different from the marked duplicate. — Jens Piegsa, Apr 24 '18 at 09:00
We have at least: UPPERCASE, lowercase, camelCase, PascalCase, snake_case, SCREAMING_SNAKE_CASE, hyphen-case, dot.case. — Jens Piegsa, Apr 24 '18 at 09:03

score 114 · Accepted Answer · edited Feb 04 '17 at 16:53

114

Guava supports this through its CaseFormat class

import com.google.common.base.CaseFormat;


public class StackOverflow25680258 {

    public static void main(String[] args) {
        System.out.println(CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.UPPER_CAMEL, "input_in_snake_case")); 
    }

}

Output

InputInSnakeCase

edited Feb 04 '17 at 16:53

jneuendorf

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answered Sep 05 '14 at 07:04

Adam

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I have the same issue. But if word is helloFunnyWORLD, result should be hello-funny-world. Guava solution is not suitable for me. – Alexey Smirnov Jun 02 '17 at 20:15
1

Just out of curiosity why is the class name `StackOverflow25680258`? Do you have some sort of macro? – SureshS Mar 02 '18 at 10:30
1

@SureshS: the name of the method is given by the id of this question - see browser link :) – Paul May 26 '18 at 11:56
@Adam Is it possible to output: "inputInSnakeCase" ? I mean with first letter in lower case. (using guava not manually lower first letter) – Lucke Sep 04 '18 at 10:13
3

@Lucke Yes - use CaseFormat.LOWER_CAMEL instead of CaseFormat.UPPER_CAMEL – Adam Sep 04 '18 at 14:15

score 0 · Answer 2 · answered Oct 30 '22 at 20:32

A java solution without dependencies assuming the input is actually snake case.

  public static String makeCamelCase(final String snakeCase) {
    var sb = new StringBuilder();
    var lastChar = snakeCase.charAt(0);
    sb.append(Character.toUpperCase(lastChar));
    for (int i =1; i < snakeCase.length(); i++) {
      var c = snakeCase.charAt(i);
      sb.append(c);
      if (lastChar == '_') {
        sb.delete(sb.length()-2, sb.length());
        sb.append("_" + Character.toUpperCase(c));
      }
      lastChar = c;
    }
    return sb.toString();
  }

Converting a string from snake case to camel case in Java

2 Answers2

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