java - 安卓日历: Get to the future day

Question

我想为用户选择的特定日期设置闹钟，当我设置为当天的前一天时，它会将其设置为过去的日期，我希望将其设置为 future 的日期。

这是我的日历设置代码:

Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.HOUR_OF_DAY, hour.getHour());
calendar.set(Calendar.MINUTE, 0);
calendar.set(Calendar.SECOND, 0);
calendar.set(Calendar.AM_PM, Calendar.AM);
calendar.set(Calendar.DAY_OF_WEEK, Calendar.Monday);

假设今天是星期四，当我将日期设置为星期一时，我希望将其设置为 4 天后，但它设置为 3 天前，即过去的星期一

Answer 1

您可以使用以下“技术”:

1. 计算当前日期与您想要设置为 future 日历的日期之间的天数差异，例如这样

   //future date
   Calendar thatDay = Calendar.getInstance();
   thatDay.set(Calendar.HOUR_OF_DAY, hour.getHour());
   thatDay.set(Calendar.MINUTE, 0);
   thatDay.set(Calendar.SECOND, 0);
   thatDay.set(Calendar.AM_PM, Calendar.AM);
   thatDay.set(Calendar.DAY_OF_WEEK, Calendar.Monday);
   
   //current date
   Calendar newDay = Calendar.getInstance();
   
   long diff = thatDay.getTimeInMillis() - newDay.getTimeInMillis(); //result in millis
   
   //result in days
   long days = diff / (24 * 60 * 60 * 1000);
   

2. 将您在步骤 1 中计算出的天数添加到日历中，例如:

   Calendar calendar = Calendar.getInstance();
   calendar.set(Calendar.HOUR_OF_DAY, hour.getHour());
   calendar.set(Calendar.MINUTE, 0);
   calendar.set(Calendar.SECOND, 0);
   calendar.set(Calendar.AM_PM, Calendar.AM);
   calendar.add(Calendar.DATE, daysCount); // Add daysCount days to current date