Random Character pull

public char[] pieceGenerator(int difficulty){
        char[] piece = new char[3];
        Random rng = new Random();
        for(int i = 0; i < 3; i++){
            int charNum =(int)rng.nextDouble()*difficulty + 61;
            char placementChar = (char) charNum;
            piece[i] = placementChar;
        }
        return piece;
    }