Question

我试图从当前日期撤退一定天数；它可以工作到24天，但在25天后它会增加几天而不是撤退...

你们中的任何人都可以理解为什么吗？

import java.sql.Timestamp

val retreve_days: ((Int) => java.sql.Timestamp) = (nb_days: Int) => {
new java.sql.Timestamp(System.currentTimeMillis()- nb_days*24*60*60*1000)
} 

val today = retreve_days(0)
// today: java.sql.Timestamp = 2019-03-01 15:43:41.418

val minus1d = retreve_days(1)
// minus1d: java.sql.Timestamp = 2019-02-28 15:43:41.958

val minus10d = retreve_days(10)
// minus10d: java.sql.Timestamp = 2019-02-19 15:43:42.502

val minus20d = retreve_days(20)
// minus20d: java.sql.Timestamp = 2019-02-09 15:43:42.895

val minus23d = retreve_days(23)
//minus23d: java.sql.Timestamp = 2019-02-06 15:43:43.245

val minus24d = retreve_days(24)
//minus24d: java.sql.Timestamp = 2019-02-05 15:43:43.577

val minus25d = retreve_days(25)
//minus25d: java.sql.Timestamp = 2019-03-26 08:46:31.817

谢谢！

Answer 1

对于25类型，Int天的计算量太大：

25 * 24 * 60 * 60 * 1000 
// mathematical value is 2160000000

Int.MaxValue
// 2147483647

// we can see the calculation is larger, this is why it becomes negative, therefore *adding* more time.

您可以采取的补救措施是将其更改为Long以进行适当的计算，这可以通过在适当的位置添加.toLong来完成：

val retrieve_days: Int => java.sql.Timestamp = (nb_days: Int) => {
    new java.sql.Timestamp(System.currentTimeMillis()- nb_days.toLong*24*60*60*1000)
} 

val minus25d = retrieve_days(25)
// minus25d: java.sql.Timestamp = 2019-02-04 10:09:48.613

从System.currentTimeMillis（）中撤退几天-错误

1 个答案: