An improved version of Listing 2-2 in Clean Code By Robert C. Martin

GuessStatisticMessage.java

import com.google.common.collect.ImmutableMap;
import java.util.function.BiFunction;

/**
 * @author Chad Befus
 * This is my attempt at an improvement on Listing 2-2 of "Clean Code" by Robert C. Martin
 */
public class GuessStatisticMessage {

    public final char candidate;
    public final String number;
    public final String verb;
    public final String pluralModifier;

    private static ImmutableMap<Integer, BiFunction<Integer, Character, GuessStatisticMessage>> conditionalBuilders =
            ImmutableMap.of(
                    0, (count, candidate) -> new GuessStatisticMessage(candidate, "no", "are", "s"),
                    1, (count, candidate) -> new GuessStatisticMessage(candidate, "1", "is", ""),
                    2, (count, candidate) -> new GuessStatisticMessage(candidate, Integer.toString(count), "are", "s")
            );
    private static int DEFAULT_BUILDER_KEY = 2;

    private GuessStatisticMessage(
            final char candidate,
            final String number,
            final String verb,
            final String pluralModifier
    ) {
        this.candidate = candidate;
        this.number = number;
        this.verb = verb;
        this.pluralModifier = pluralModifier;
    }

    public static GuessStatisticMessage fromCountAndCandidate(final int count, final char candidate) {
        return conditionalBuilders.getOrDefault(count, DEFAULT_BUILDER_KEY).apply(count, candidate);
    }

    @Override
    public String toString() {
        return String.format("There %s %s %s%s", verb, number, candidate, pluralModifier);
    }
}

GuessStatisticMessageOriginal.java

/**
 * @author Robert C. Martin
 * This is Listing 2-2 of "Clean Code" by Robert C. Martin
 */
public class GuessStatisticMessageOriginal {
    private String number;
    private String verb;
    private String pluralModifier;

    public String make(char candidate, int count) {
        createPluralDependentMessageParts(count);
        return String.format(
                "There %s %s %s%s",
                verb, number, candidate, pluralModifier );
    }

    private void createPluralDependentMessageParts(int count) {
        if (count == 0) {
            thereAreNoLetters();
        } else if (count == 1) {
            thereIsOneLetter();
        } else {
            thereAreManyLetters(count);
        }
    }

    private void thereAreManyLetters(int count) {
        number = Integer.toString(count);
        verb = "are";
        pluralModifier = "s";
    }

    private void thereIsOneLetter() {
        number = "1";
        verb = "is";
        pluralModifier = "";
    }

    private void thereAreNoLetters() {
        number = "no";
        verb = "are";
        pluralModifier = "s";
    }
}

I argue that this is better because:

1. There is an obvious way to construct this using a named static method (and still only one way to do so).
2. We can easily add new cases to the map (imagine a different case for the number 3) and also easily change the default functionality.
3. We now have an Immutable object representing the collection of values extracted from count and candidate that can be used as more than just a String.
4. This object can be used as a string because it overrides the toString() function of java's base object.