使用常量单位添加日期之间的差异

Question

我需要保持第一次迭代的开始日期不变，并添加带有单位的结束日期，迭代应该发生，直到开始日期在结束数据之前。

例：

开始日期 （1/1/2015） 和结束日期 （12/31/2015） 之间的差异为 12 个月

单位为4个月

那我应该得到

Contract    Start date      End date
1           1/1/2015        4/31/2015
2           5/1/2015        8/31/2015
3           9/1/2015        12/31/2015

我试过的代码：

 private void contractDetails(List<PolicyPeriodFormulaType> policyPeriod ){

     for (PolicyPeriodFormulaType policyPeriodFormulaType : policyPeriod) {
         Date effectiveDateFrom = policyPeriodFormulaType.getEffectivePeriod().getEffectiveFrom();
         Date effectiveDateTo = policyPeriodFormulaType.getEffectivePeriod().getEffectiveTo();
         Instant effectiveFrom = effectiveDateFrom.toInstant();
         ZonedDateTime zdt = effectiveFrom.atZone(ZoneId.systemDefault());
         LocalDate fromDate = zdt.toLocalDate();
         Instant effectiveTo = effectiveDateTo.toInstant();
         ZonedDateTime zdt1 = effectiveTo.atZone(ZoneId.systemDefault());
         LocalDate toDate = zdt.toLocalDate();

         int unit = policyPeriodFormulaType.getUnits();
         String unitMeasurement = policyPeriodFormulaType.getUnitOfMeasurement();
         Period p = Period.between(fromDate,toDate);
         int months = p.getMonths();
         int years = p.getYears();
         if(unitMeasurement.equalsIgnoreCase("Month")){
             months = months+(years*12);
         }
         int duration = months/unit; // 12/4 = 3
         int i =0;
         while(fromDate.isBefore(toDate)){
             fromDate=fromDate;
             toDate=fromDate.plusMonths(unit);
             fromDate=toDate.plusMonths(unit);
         }

    }

 }

Answer 1

坦率地说，你应该以某种形式使用 Java 8 的 Date/Time API 或 Joda-Time，例如......

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("MM/dd/yyyy");
LocalDate startDate = LocalDate.parse("01/01/2015", dtf);
LocalDate endDate = LocalDate.parse("12/31/2015", dtf);
LocalDate date = startDate;
Period period = Period.parse("P4M");
// or 
//Period period = Period.ofMonths(4);
// or 
//Period period = Period.of(0, 4, 0);
while (date.isBefore(endDate)) {
    LocalDate to = date.plus(period);
    System.out.println(dtf.format(date) + " - " + dtf.format(to.minusDays(1)));
    date = to;
}

哪些打印

01/01/2015 - 04/30/2015
05/01/2015 - 08/31/2015
09/01/2015 - 12/31/2015

由此，创建一个容器类（即Contract样式类）来包含 to-from 值并不难。然后，您可以使用Comparable或Comparator将它们按某种List或数组进行排序