What to do?

package hangman;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Hangman {
    ...

    public static void main(String[] args) {
        String sentence = "example";
        StringBuilder sentenceLengthInCharacters = new StringBuilder("-".repeat(sentence.length()));
        Scanner input = new Scanner(System.in);
       ...
        StringBuilder correctCharsEntered = new StringBuilder();
        StringBuilder incorrectCharsEntered = new StringBuilder();
        while(correctCharsEntered.length() != sentence.length() + 2){
            char human = input.next().charAt(0);
            correctCharsEntered.append(human);
            if(!sentence.contains(correctCharsEntered)){
                incorrectCharsEntered.append(correctCharsEntered.charAt(correctCharsEntered.length()-1));
                ....
                correctCharsEntered.deleteCharAt(correctCharsEntered.length()-1);

            }/*else{
                // i should replace - with the index of all the places where that char appears
                    System.out.println("Replacing " + sentenceLengthInCharacters);
            }*/
            else{
                for (int i = 0; i < sentence.length(); i++){
                    // i should replace - with the index of all the places where that char appears
                    if(sentence.charAt(i) == correctCharsEntered.charAt(correctCharsEntered.length()-1)){
                        sentenceLengthInCharacters.setCharAt(i,correctCharsEntered.charAt(correctCharsEntered.length()-1));
                        System.out.println(i);
                        System.out.println(correctCharsEntered);
                        System.out.println(correctCharsEntered.length()-1);
                        System.out.println(correctCharsEntered.charAt(correctCharsEntered.length()-1));
                        System.out.println(sentenceLengthInCharacters);
                        break;
                    }
                }
            }
        }
    }
}