Java中"if then else“语句的替代哈希表

public int getDaysInMonth(String month) {
    if ("January".equals(month)) {
        return 31;
    } else if ("February".equals(month)) {
        return 28; // 忽略闰年
    } else if ("March".equals(month)) {
        return 31;
    }
    // ... 其他月份
    else {
        throw new IllegalArgumentException("Invalid month");
    }
}

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

public class MonthDays {
    private static final Map<String, Integer> monthDays = new HashMap<>();

    static {
        monthDays.put("January", 31);
        monthDays.put("February", 28); // 忽略闰年
        monthDays.put("March", 31);
        // ... 其他月份
    }

    public int getDaysInMonth(String month) {
        Integer days = monthDays.get(month);
        if (days == null) {
            throw new IllegalArgumentException("Invalid month");
        }
        return days;
    }
}