LottoNumber.java

package step2.domain;

import java.util.HashMap;
import java.util.Map;

public class LottoNumber implements Comparable<LottoNumber> {
    private static final int MIN_NUMBER = 1;
    private static final int MAX_NUMBER = 45;
    private static final Map<Integer, LottoNumber> CACHE = new HashMap<>();

    static {
        for (int i = MIN_NUMBER; i <= MAX_NUMBER; i++) {
            CACHE.put(i, new LottoNumber(i));
        }
    }

    private final int number;

    private LottoNumber(int number) {
        this.number = number;
    }

    public static LottoNumber from(int number) {
        if (number < MIN_NUMBER || number > MAX_NUMBER) {
            throw new IllegalArgumentException(
                    String.format("숫자는 %d보다 크거나 같고, %d보다 작아야 합니다.", MIN_NUMBER, MAX_NUMBER));
        }
        return CACHE.get(number);
    }

    public int getNumber() {
        return number;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof LottoNumber)) return false;
        LottoNumber that = (LottoNumber) o;
        return number == that.number;
    }

    @Override
    public int hashCode() {
        return Integer.hashCode(number);
    }

    @Override
    public int compareTo(LottoNumber other) {
        return Integer.compare(this.number, other.number);
    }

    @Override
    public String toString() {
        return String.valueOf(number);
    }
}