Hi There. Getting some compiler errors and not too sure why

I'm doing the Java Basics tutorials - Java Objects - Exceptions

class Game{ private String answer; private String hits; private String misses;

public Game(String answer){ this.answer = answer; hits = ""; misses = ""; }

public boolean applyGuess (char letter) { if (misses indexOf(letter) != -1 || hits.indexOf(letter) != -1){ throw new IllegalArgumentException(letter + " has already been guessed"); }

boolean isHit = answer.indexOf(letter) != -1;
if (isHit) {
  hits += letter;
} else {
  misses += letter;
}
return isHit;

}

public String getCurrentProgress(){ String progress = ""; for (char letter : answer.toCharArray()){ char display = '-'; if(hits.indexOf(letter) != -1){ display = letter; } progress += display; } return progress; } }