将日期时间字符串格式化为仅时间

发布于 2024-10-14 01:22:38 字数 724 浏览 4 评论 0原文

我正在从 SQLite DB 中检索日期时间，其格式为...

2011-01-24 02:45:00

在 C# 中，我可以简单地使用 DateTime.Parse("2011-01-24 02:45:00").ToString("HH :mm") 以获取字符串 02:45

他们是我可以在 Android/Java 中执行此操作的方法吗？我的 Android 应用程序中的代码如下所示...

// dateStr below is logging as correctly being yyyy-MM-dd HH:mm:ss format
String dateStr = cursor.getString(cursor.getColumnIndex("start_time"));
SimpleDateFormat sdf = new SimpleDateFormat("HH:mm");
String shortTimeStr = sdf.format(dateStr); // <-- throws IllegalArgumentException

编辑：感谢 doc_180 和 Konstantin Burov - 给出的示例帮助我解决了问题。部分问题是我导入的是 java.sql.Date 而不是 java.util.Date。我已经改变了一些事情，现在它对我来说非常有效。

原文

I'm retrieving a datetime from a SQLite DB which comes out in the format...

2011-01-24 02:45:00

In C# I can simply use DateTime.Parse("2011-01-24 02:45:00").ToString("HH:mm") in order to get the string 02:45

Is their a way I can I do this in Android/Java? My code in my Android app looks like this...

// dateStr below is logging as correctly being yyyy-MM-dd HH:mm:ss format
String dateStr = cursor.getString(cursor.getColumnIndex("start_time"));
SimpleDateFormat sdf = new SimpleDateFormat("HH:mm");
String shortTimeStr = sdf.format(dateStr); // <-- throws IllegalArgumentException

EDIT: Thanks to both doc_180 and Konstantin Burov - the examples given have helped me sort out the problem. Part of the issue was that I was importing java.sql.Date instead of java.util.Date. I've changed things around and it's working perfectly for me now.

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白色秋天 2024-10-21 01:22:38

当您传递字符串时，SimpleDateFormat.format 需要日期或日历作为参数。首先将字符串转换为日期。

String dateStr = cursor.getString(cursor.getColumnIndex("start_time"));
SimpleDateFormat toFullDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date fullDate = toFullDate.parse(dateStr);
SimpleDateFormat sdf = new SimpleDateFormat("HH:mm");
String shortTimeStr = sdf.format(fullDate);

是的，我宁愿将日期存储在数据库中，因此获取 Date 对象会更加简单：

Long dateMilliseconds = cursor.getLong(cursor.getColumnIndex("start_time"));
Date fullDate = new Date(dateMilliseconds);

SimpleDateFormat.format expects Date or Calendar as argument while you're passing a String. Convert the String into Date first.

String dateStr = cursor.getString(cursor.getColumnIndex("start_time"));
SimpleDateFormat toFullDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date fullDate = toFullDate.parse(dateStr);
SimpleDateFormat sdf = new SimpleDateFormat("HH:mm");
String shortTimeStr = sdf.format(fullDate);

And yeah, I'd rather stored date as long in the database, so getting a Date object then would be more trivial:

Long dateMilliseconds = cursor.getLong(cursor.getColumnIndex("start_time"));
Date fullDate = new Date(dateMilliseconds);

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永言不败 2024-10-21 01:22:38

您需要执行以下操作。

try {
   Date date = null;
   date = df.parse("2011-01-24 02:45:00");
   SimpleDateFormat sdf = new SimpleDateFormat("HH:mm");
   String shortTimeStr = sdf.format(date);
   System.out.println(shortTimeStr);
} catch (ParseException e) {
   // To change body of catch statement use File | Settings | File Templates.
   e.printStackTrace(); 
}

正如我在评论中提到的，您应该将时间存储为毫秒而不是字符串。否则，除了创建中间人对象 Date 之外，我没有看到任何其他方法。

You need to do the following.

try {
   Date date = null;
   date = df.parse("2011-01-24 02:45:00");
   SimpleDateFormat sdf = new SimpleDateFormat("HH:mm");
   String shortTimeStr = sdf.format(date);
   System.out.println(shortTimeStr);
} catch (ParseException e) {
   // To change body of catch statement use File | Settings | File Templates.
   e.printStackTrace(); 
}

As I mentioned in comment, you should store the time as milliseconds instead of string. Otherwise, I do not see any other way than creating a middleman object Date.

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