//정적 유틸리티
public class SpellChecker {
    private static final Lexicon dictionary = new Lexicon("english"); // 사전이 하나뿐이다.

    private SpellChecker() {} // 객체 생성 방지

    public static boolean isValid(String word) {...}
    public static List<String> suggestions(String typo) {...}
}

public class Main {
	public static void main(String[] args) {
		SpellChecker.isValid("hypopotamus");
  }
}

//싱글턴
public class SpellChecker {
    private final Lexicon dictionary = new Lexicon(); // 사전이 하나뿐이다

    private SpellChecker() {} // 객체 생성 방지
    public static SpellChecker INSTANCE = new SpellChecker();

    public boolean isValid(String word) {}
    public List<String> suggestions(String type) {}
}

public class Main {
	public static void main(String[] args) {
		SpellChecker.INSTANCE.isValid("Hippopotamus");
  }
}

// 의존 객체 주입 패턴
public class SpellChecker {
    private final Lexicon dictionary;

    public SpellChecker(Lexicon dictionary) {
        this.dictionary = Objects.requireNonNull(dictionary);
    }

    public boolean isValid(String word) { return false;}
    public List<String> suggestions(String typo) { return null;}
}

Mosaic create(Supplier<? extends Tile> tileFactory) { ... }