java-8 - Set<LocalDate> 包含 LocalDate 最佳实践

Question

我有:

ZoneId gmt = ZoneId.of("GMT");
LocalDateTime localDateTime = LocalDateTime.now();
LocalDate localDateNow = localDateTime.toLocalDate();

Set<LocalDate> hollidays = new HashSet<>();

我可以像这样等于 LocalDate 吗？

if(hollidays.contains(localDateNow)){
...
}

Answer 1

是的，可以。

如果您查看 LocalDate::equals() 实现，您将能够看到:

int compareTo0(LocalDate otherDate) {
    int cmp = (year - otherDate.year);
    if (cmp == 0) {
        cmp = (month - otherDate.month);
        if (cmp == 0) {
            cmp = (day - otherDate.day);
        }
    }
    return cmp;
}

这看起来像是一个正确实现的日期equals方法 - 这意味着它可以与HashSet一起正常工作。

摘自 hashCode() 文档:

If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.