java - 大长数字除以舍入

Question

我在使用java时遇到问题，然后我想除以大长型数字，例如，如果我除以165600139/86400000 = 1.9，但我的方法返回1而不进行四舍五入:/

public static long calcDaysBefore(Date date) {
    int MILISECONDS_IN_DAY = 24 * 60 * 60 * 1000;
    long days = 0;
    if (date != null) {
        long current = getCurrentDate().getTime() - date.getTime();
        days = current / MILISECONDS_IN_DAY;
    }
    return days;
}

Answer 1

向下取整，类似于doing

days = Math.floor((double) current / MILISECONDS_IN_DAY);

如果你想四舍五入，你可以写

days = (current + MILISECONDS_IN_DAY/2) / MILISECONDS_IN_DAY;

使用浮点，您可以使用以下慢得多的方法。

days = Math.round((double) current / MILISECONDS_IN_DAY);

如果你想四舍五入，你可以这样做

days = (current + MILISECONDS_IN_DAY-1) / MILISECONDS_IN_DAY;

或

days = Math.ceil((double) current / MILISECONDS_IN_DAY);

顺便说一句，毫秒有两个 l