如何在Java中从一个Date对象中减去X day？

Question

Date date = new Date(); // current date
date = date - 300; // substract 300 days from current date and I want to use this "date"

怎么做？

Answer 1

对于Java8的日期时间API更改，使用localdate

LocalDate date = LocalDate.now().minusDays(300);

同样，您也可以

LocalDate date = someLocalDateInstance.minusDays(300);

有关java.util.date<-->java.time.LocalDateTime之间的转换，请参阅https://stackoverflow.com/A/23885950/260990

Date in = new Date();
LocalDateTime ldt = LocalDateTime.ofInstant(in.toInstant(), ZoneId.systemDefault());
Date out = Date.from(ldt.atZone(ZoneId.systemDefault()).toInstant());

Calendar cal = Calendar.getInstance();
cal.setTime(dateInstance);
cal.add(Calendar.DATE, -30);
Date dateBefore30Days = cal.getTime();