简化用“今天”替换日期对象和“昨天” Java静态方法中的字符串
我有以下方法,如果没有别的办法的话,我想让它变得更短或更快。欢迎所有评论:
Bellow 方法接受一个日期对象,对其进行格式化(“EEE hh:mma MMM d, yyyy”),然后确定日期是今天还是昨天,如果是,则返回“(昨天| 今天) hh:mma" 格式的字符串。
public static String formatToYesterdayOrToday(String date) {
SimpleDateFormat sdf = new SimpleDateFormat("EEE hh:mma MMM d, yyyy");
Date in = null;
try {
in = sdf.parse(date);
} catch (ParseException e) {
log.debug("Date parsing error:", e);
}
Calendar x = Calendar.getInstance();
x.setTime(in);
String hour = Integer.toString(x.get(Calendar.HOUR));
String minute = Integer.toString(x.get(Calendar.MINUTE));
String pm_am = x.get(Calendar.AM_PM) == Calendar.AM ? "AM" : "PM";
x.set(Calendar.HOUR, 0);
x.set(Calendar.HOUR_OF_DAY, 0);
x.set(Calendar.MINUTE, 0);
x.set(Calendar.SECOND, 0);
x.set(Calendar.MILLISECOND, 0);
Calendar today = Calendar.getInstance();
today.set(Calendar.HOUR, 0);
today.set(Calendar.HOUR_OF_DAY, 0);
today.set(Calendar.MINUTE, 0);
today.set(Calendar.SECOND, 0);
today.set(Calendar.MILLISECOND, 0);
Calendar yesterday = Calendar.getInstance();
yesterday.set(Calendar.HOUR, 0);
yesterday.set(Calendar.HOUR_OF_DAY, 0);
yesterday.set(Calendar.MINUTE, 0);
yesterday.set(Calendar.SECOND, 0);
yesterday.set(Calendar.MILLISECOND, 0);
yesterday.add(Calendar.DATE, -1);
if (x.compareTo(today) == 0) {
return "Today " + hour + ":" + minute + pm_am;
}
if (x.compareTo(yesterday) == 0) {
return "Yesterday " + hour + ":" + minute + pm_am;
}
return date;
}
I have following method that I would like to make shorter or faster if nothing else. Please all comments are welcome:
Bellow method takes a date object, formates it ("EEE hh:mma MMM d, yyyy") and then figures out if the date is today or yesterday and than, if it is, it returns "(Yesterday | Today) hh:mma" formated string.
public static String formatToYesterdayOrToday(String date) {
SimpleDateFormat sdf = new SimpleDateFormat("EEE hh:mma MMM d, yyyy");
Date in = null;
try {
in = sdf.parse(date);
} catch (ParseException e) {
log.debug("Date parsing error:", e);
}
Calendar x = Calendar.getInstance();
x.setTime(in);
String hour = Integer.toString(x.get(Calendar.HOUR));
String minute = Integer.toString(x.get(Calendar.MINUTE));
String pm_am = x.get(Calendar.AM_PM) == Calendar.AM ? "AM" : "PM";
x.set(Calendar.HOUR, 0);
x.set(Calendar.HOUR_OF_DAY, 0);
x.set(Calendar.MINUTE, 0);
x.set(Calendar.SECOND, 0);
x.set(Calendar.MILLISECOND, 0);
Calendar today = Calendar.getInstance();
today.set(Calendar.HOUR, 0);
today.set(Calendar.HOUR_OF_DAY, 0);
today.set(Calendar.MINUTE, 0);
today.set(Calendar.SECOND, 0);
today.set(Calendar.MILLISECOND, 0);
Calendar yesterday = Calendar.getInstance();
yesterday.set(Calendar.HOUR, 0);
yesterday.set(Calendar.HOUR_OF_DAY, 0);
yesterday.set(Calendar.MINUTE, 0);
yesterday.set(Calendar.SECOND, 0);
yesterday.set(Calendar.MILLISECOND, 0);
yesterday.add(Calendar.DATE, -1);
if (x.compareTo(today) == 0) {
return "Today " + hour + ":" + minute + pm_am;
}
if (x.compareTo(yesterday) == 0) {
return "Yesterday " + hour + ":" + minute + pm_am;
}
return date;
}
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这是今天、昨天、明天
this for today,yesterday,tomorrow
看看乔达时间:
http://joda-time.sourceforge.net/
这是文档中的一些示例代码:
Look at jodatime:
http://joda-time.sourceforge.net/
this is some example code from the doc:
这是 Balusc 实现的扩展版本。
试试这个,我使用 joda-datatime2.2.jar 和 SimpleDateFormat 实现了它
使用和测试 Util 类的简单案例:
This is extended versino of Balusc's implementation.
Try this, i implemented it using joda-datatime2.2.jar and SimpleDateFormat
Simple cases to use and test the Util class:
我知道我参加这个聚会迟到了。但我对这个问题有最短的解决方案。
如果您想根据日期显示“今天”或“昨天” 那么你只需要
在这里使用这个变量 date 就是 Date 对象。
I know I am late to this party. But I have shortest solution for this problem.
If you want to show "Today" or "Yesterday" based on the Date then you just need to use this
here variable date is the Date object.
以下是如何使用标准 API 改进它:
以下是如何使用 Jodatime 进行改进:
Here's how you could improve it with the standard API:
Here's how you could do it with Jodatime:
您写了“欢迎所有评论”,所以这是我使用 joda-time 的方式。 :)
我喜欢以 iPhone 最近通话的简短而智能的方式显示日期和时间(类似于 google wave posts)。如果是今天,则为“hh:mm”;如果<7 天,则为“昨天”或工作日名称,否则yyyy-MM-dd 。
我使用一组 SimpleDateFormat (如上面的 weekdayFormat)将时间格式化为所需的字符串,其中 DateTime 和 DateMidnight 是 joda-time 类。
在这些情况下,两个 DateTime:s 之间经过的天数不如人们如何定义谈论它的时间相关。 DateMidnight 在这里很方便,而不是像我看到的一些人那样计算天数(或毫秒),尽管其他方法也可以工作。 :)
You wrote "all comments welcome" so here's my way using joda-time. :)
I am a fan of displaying dates and times in the short and smart way of iPhone's recent calls (similar to google wave posts). That is "hh:mm" if today, "yesterday" or name of weekday if <7 days, else yyyy-MM-dd.
where I use a set of SimpleDateFormat (as weekdayFormat above) to format the time to the desired strings, and where DateTime and DateMidnight are joda-time classes.
In these cases the number of elapsed days between two DateTime:s is less relevant than how people would define the time talking about it. Instead of counting days (or milliseconds as I've seen some people do) DateMidnight comes handy here, though other methods would work just as well. :)
我对这个问题的理解是提供一种简单的方法来产生如下输出:
下面的代码对我有用,但我对android很陌生,也许其他人可以指出代码是否不健壮。在下面的代码中,“timeLong”是我的事件的时间(以纪元时间(毫秒)为单位)。
my understanding of the question is provide a simple method to produce output like the following:
the code below worked for me, but i am new to android and maybe others could point out if the code is not robust. in code below 'timeLong' is the time of my events in epoch time (milliseconds).
时区
问题和其他答案忽略了时区的关键问题。该输入字符串缺少任何时区或offset-from-UTC。因此,该字符串将被解析,同时假设它代表 JVM 当前默认时区中的日期时间。有风险的业务,因为 (a) 假设可能是错误的,以及 (b) 默认值可能随时发生变化,甚至在运行时也是如此。
区域设置
问题和其他答案忽略了另一个关键问题:
区域设置
。 Locale 确定在解析(和生成)过程中用于翻译输入字符串中的日期名称和月份名称的人类语言。如果未指定,则将使用 JVM 当前的默认区域设置进行翻译。就像时区一样,JVM 的默认区域设置可以随时更改,甚至在运行时也是如此。
最好指定您想要/预期的区域设置。
java.time
该问题和其他答案使用旧的日期时间类,这些类已被证明设计不佳且麻烦。 Java 8 及更高版本具有 java.time 内置框架,其类取代了旧的类。
在生成新字符串时解析字符串的方法应分为两个方法。一种方法应该解析以获取日期时间对象。第二个应该采用日期时间对象并生成所需的字符串输出。然后每个都可以单独使用。这种方法使我们不再将字符串视为日期时间值。字符串是日期时间值的文本表示。您的业务逻辑应该专注于将这些日期时间值作为对象进行操作,而不是专注于字符串。
解析
生成
给定上述方法中的
ZonedDateTime
,我们可以使用指定的区域设置生成其日期时间值的文本表示形式,以翻译日期名称和月份名称。为了确定日期时间是今天还是昨天,我们只关心日期部分,而不关心一天中的时间。为此,我们可以使用
LocalDate
java.time 中的类。示例
练习这两种方法。
任意选择时区
America/New_York
,因为问题没有指定。顺便说一句,您可以要求 java.time 根据区域设置的文化规范自动格式化输出字符串,而不是硬编码格式。
转储到控制台。
顺便说一句,我建议在
AM
或PM
之前添加一个空格,以便于阅读。Time Zone
The Question and the other Answers ignore the crucial issue of time zone. That input string lacks any time zone or offset-from-UTC. So that string will be parsed while assuming it represents a date-time in your JVM’s current default time zone. Risky business as (a) that assumption may be false, and (b) that default can change at any moment, even during runtime.
Locale
The Question and other Answers ignore another crucial issue:
Locale
. The Locale determines the human language used to translate the name of day and name of month from the input string during parsing (and generating).If not specified the JVM’s current default Locale will be used for translation. Just as with time zone, your JVM’s default Locale can change at any moment, even during runtime.
Better to specify your desired/expected Locale.
java.time
The Question and the other Answers use the old date-time classes that have proven to be poorly designed and troublesome. Java 8 and later has the java.time framework built-in whose classes supplant the old ones.
You method to parse a string while generating a new string should be broken up into two methods. One method should parse to obtain date-time objects. The second should take date-time objects and generate the desired string output. Then each can be used separately. And this approach leads us away from thinking of strings as date-time values. Strings are textual representations of date-time values. Your business logic should focus on manipulating those date-time values as objects, not focus on strings.
Parsing
Generating
Given a
ZonedDateTime
in hand from the method above, we can generate a textual representation of its date-time value using a specified Locale for translation of name-of-day and name-of-month.To determine if the date-time is for today or yesterday, we only care about the date portion without time of day. For that we can use the
LocalDate
class in java.time.Example
Exercise those two methods.
Arbitrarily choosing a time zone of
America/New_York
as the Question does not specify.By the way, you can ask java.time to automatically format the output string according to the cultural norms of the Locale instead of hard-coding a format.
Dump to console.
By the way, I suggest putting a SPACE before the
AM
orPM
for easier reading.除了上面接受的答案之外,使用 java.util.Date.getTime() 比较日期的另一种方法(注意:应该使用 long 而不是 int):
<%=days%>会返回:
Another way of comparing dates apart from the accepted answer above using java.util.Date.getTime() (note: long should be used instead of int):
<%=days%> would return: