java - 将日历集 DAY_OF_WEEK 转换为使用 TemporalAdjusters

Question

我有一些像这样的遗留代码

        final Calendar cal = new GregorianCalendar();
        cal.setTime(today);
        // changed on May-03-2004
        //cal.set(Calendar.DAY_OF_WEEK, cal.getFirstDayOfWeek());
        if (cal.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY) {
            cal.add(Calendar.DAY_OF_YEAR, -6);
        } else {
            cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
        }
        //System.out.println("Begin of cycle: " + cal.getTime());

我想将其转换为使用 java.time TemporalAdjuster 类，以使其更具可读性。

但我不太确定如何解释https://stackoverflow.com/a/1319484/242042使行为匹配。

Answer 1

假设今天确实是今天的日期，那么Java Time API版本，使用TemporalAdjusters ，将是:

LocalDate today = LocalDate.now();

TemporalAdjuster adjuster = TemporalAdjusters.previousOrSame(DayOfWeek.MONDAY);
LocalDate monday = today.with(adjuster);

System.out.println(today + " -> " + monday);

示例输出

2020-02-01 -> 2020-01-27

2020-02-01 是星期六，2020-01-27 是前一个星期一。