can someone give a code for Game.java mines is not working

public class Game { 
  private String mAnswer; 
  private String mHits; 
  private String mMisses;

  public Game(String answer) 
  { mAnswer = answer; mHits = ""; mMisses = ""; }

  public boolean applyGuess(char letter) 
  { 
    boolean isHit = mAnswer.indexOf(letter) >= 0; 
    if (isHit) 
    {
      mHits += letter; 
    } else {
      mMisses += letter; 
    } 
    return isHit; 
  }
  public String getCurrentProgress() {
    String progress = "";
    for (char letter: mAnswer.toCharArray()) {
      char display = '_';
      if (mHits.indexOf(letter)) >= 0 {
        display = letter;
      }
      progress += display;


    }
    return progress;
  }

}