Shifted Java Date已成为过去(Shifted Java Date is in the past)

Shifted Java Date已成为过去(Shifted Java Date is in the past) java

我有一个问题，我不能理解 - 如果我添加超过24天，过去的转移日期。

long start = System.currentTimeMillis(); long shift = 3600000 * 24 * 24; System.out.println(new Date(start)); System.out.println(new Date(start + shift));

24天班次：

start - Wed Apr 18 11:37:12 CEST 2012 end - Sat May 12 11:37:12 CEST 2012

25天班次：

start - Wed Apr 18 11:37:55 CEST 2012 end - Sat Mar 24 17:35:08 CET 2012

有人可以告诉我为什么它会这样吗？ 谢谢。

I have a problem I can't uderstand - if I add more than 24 days, the shifted date in the past.

long start = System.currentTimeMillis(); long shift = 3600000 * 24 * 24; System.out.println(new Date(start)); System.out.println(new Date(start + shift));

For 24 day shift:

start - Wed Apr 18 11:37:12 CEST 2012 end - Sat May 12 11:37:12 CEST 2012

For 25 day shift:

start - Wed Apr 18 11:37:55 CEST 2012 end - Sat Mar 24 17:35:08 CET 2012

Could someone advise me why it behaves this way? Thank you.

最满意答案

你正在进行整数乘法，然后将结果转换为long。 乘法溢出，因此结果为负。

使用以下代码进行长乘法运算：

long shift = 3600000L * 24 * 24;

You're doing Integer multiplication, and then transforming the result into a long. The multiplication overflows, so the result is negative.

Use the following code to do long multiplication:

long shift = 3600000L * 24 * 24;