java - 在 Java 中与时间交互

Question

如何在 Java 中随时间进行加减？例如，我正在编写一个程序，当您输入就寝时间时，它会加上 90 分钟(1 个 sleep 周期的长度)来告诉您理想的起床时间。

Scanner input;
input = new Scanner (System.in);

int wakeup0;
int wakeup1;
int wakeup2;
int wakeup3;
int wakeup4;
int wakeup5;

System.out.println("When will you be going to bed?");
int gotobed = Integer.parseInt(input.nextLine());
wakeup0 = gotobed + 90;
wakeup1 = wakeup0 + 90;
wakeup2 = wakeup1 + 90;
wakeup3 = wakeup2 + 90;
wakeup4 = wakeup3 + 90;
wakeup5 = wakeup4 + 90;

System.out.println("You should set your alarm for: "+wakeup0+" "+wakeup1+" "+wakeup2+" "+wakeup3+" "+wakeup4+" or "+wakeup5);

如何才能使 90 与 915 相加得到 1045 而不是 1095？

Answer 1

以毫秒为单位计算一切。乍一看这似乎很不方便，但数学原理非常简单。

输入就寝时间时，您需要决定用户将如何操作。会是小时和分钟吗？是否会有 AM/PM 或 24 小时制。您将考虑哪个时区。所有这些都是通过 Calendar 或 DateFormat 类完成的，它会为您提供一个包含指定时间的长值。

之后，添加时间偏移就很容易了。

SimpleDateFormat df = new SimpleDateFormat("HHmm");
long bedttime = df.parse(inputValue).getTime();
long wakeup1 = bedttime + (90 * 60 * 1000);   //90 minutes in milliseconds.
long wakeup2 = wakeup1  + (90 * 60 * 1000);   //90 minutes in milliseconds.
long wakeup3 = wakeup2  + (90 * 60 * 1000);   //90 minutes in milliseconds.
long wakeup4 = wakeup3  + (90 * 60 * 1000);   //90 minutes in milliseconds.
long wakeup5 = wakeup4  + (90 * 60 * 1000);   //90 minutes in milliseconds.

System.out.println("The first wakeup time is "+df.format(new Date(wakeup1)));

每个 long 值都包含警报应该响起的时间。再次使用格式化程序生成该时间值的用户友好表示。