一年中的 Java 毫秒数

Question

我在 Java 中使用毫秒进行一些日期计算，并注意到以下问题:

private static final int MILLIS_IN_SECOND = 1000;
    private static final int SECONDS_IN_MINUTE = 60;
    private static final int MINUTES_IN_HOUR = 60;
    private static final int HOURS_IN_DAY = 24;
    private static final int DAYS_IN_YEAR = 365; //I know this value is more like 365.24...
    private static final long MILLISECONDS_IN_YEAR = MILLIS_IN_SECOND * SECONDS_IN_MINUTE * MINUTES_IN_HOUR * HOURS_IN_DAY * DAYS_IN_YEAR;


System.out.println(MILLISECONDS_IN_YEAR);  //Returns 1471228928

我知道 1 年大约 = 31,556,952,000 毫秒，所以我的乘法以某种方式关闭了。

谁能指出我做错了什么？我应该使用long吗？

Answer 1

Should I be using a long?

是的。问题是，由于 MILLIS_IN_SECOND 等等都是 int，当你将它们相乘时，你会得到一个 int。您正在将该 int 转换为 long，但只有 after int 乘法已经导致错误回答。

要解决此问题，您可以将第一个转换为 long:

    private static final long MILLISECONDS_IN_YEAR =
        (long)MILLIS_IN_SECOND * SECONDS_IN_MINUTE * MINUTES_IN_HOUR
        * HOURS_IN_DAY * DAYS_IN_YEAR;