How to capitalize first occurrence of character in a string-CodePudding

I have a String "aabccdeef"

Now i want to capitalize only first occurrence of each char so that the o/p is AaBCcDEeF in Java

CodePudding user response：

I would do it this way (since I love java streams)

 public static String capitalizeFirstOccurrence(String str) {
    var alreadyOccurred = new HashSet<String>();
    return str.chars()
            .mapToObj(x -> String.valueOf((char) x)) // convert to single char String
            .map(character -> {
                if (alreadyOccurred.contains(character)) {
                    return character;
                }
                alreadyOccurred.add(character);
                return character.toUpperCase();
            })
            .collect(Collectors.joining());
}

public static void main(String[] args) {
    var input = "aabccdeef";
    var output = capitalizeFirstOccurrence(input);
    System.out.println(output);
}