Flattening a Java class; no other refactorings.

GuessChar2.java

public class GuessChar2 {
    public boolean guessCharacter(char guess) throws A8InvalidInputException, A8AlreadyGuessedException {
        String sGuess = "" + guess;

        if (invalidCharacter(guess)) { // Use the string?
            throw new A8InvalidInputException(sGuess);
        }

        guess = Character.toLowerCase(guess); // Modifying a parameter?
        if (guessedCharacters.contains(guess) ) {
            throw new A8AlreadyGuessedException(sGuess);
        }

        numberOfGuessesLeft--;
        guessedCharacters.add(guess);

        return keyPhrase.contains(sGuess);
    }
}

GuessChar3.java

package com.davelnewton.guess;

public class GuessChar3 {
    public boolean guessCharacter(char guess) throws A8InvalidInputException, A8AlreadyGuessedException {
        assertValidGuess(guess);
        assertNotGuessed(guess);
        return processValidGuess(guess);
    }

    public void assertValidGuess(char guess) throws A8InvalidInputException {
        if (invalidCharacter(guess)) {
            throw new A8InvalidInputException("" + guess);
        }
    }

    public void assertNotGuessed(char guess) throws A8AlreadyGuessedException {
        guess = Character.toLowerCase(guess);
        if (guessedCharacters.contains(guess) ) {
            throw new A8AlreadyGuessedException("" + guess);
        }
    }

    public boolean processValidGuess(char guess) {
        numberOfGuessesLeft--;
        guessedCharacters.add(guess);

        return keyPhrase.contains("" + guess);
    }

}