当字符串具有"TRT"时，如何将字符串转换为日期?在里面 [英] How can i convert String to Date when it has "TRT" in it

问题描述

String sDate = "06.08.2020" // 06 day 08 month 2020 is year

这是我在txt文件中拥有的日期.我在JTable中使用它们.为了对表格进行排序，我使用此DateFormatter将它们转换为日期.

This is the date i have in my txt file. I use them in JTable. To sort the table i convert them to date with this DateFormatter.

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd.MM.yyyy");

它确实将字符串转换为日期.

And it does convert the string to date as this.

LocalDate date = LocalDate.parse(sDate,formatter);
//The date : Thu Aug 06 00:00:00 TRT 2020

现在，我需要像第一个日期 06.08.2020 一样对其进行转换.但是我不能使用 date 作为输入.因为我是从JTable中获取的，所以我以 String 的形式获取它.

Now i need to convert it like the first date 06.08.2020. But i can't use date as input. Because i get it from JTable so i get it as String.

所以我尝试了这段代码.

So i tryed this code.

String sDate1 = "Thu Aug 06 00:00:00 TRT 2020";// The date i get from JTable
LocalDate lastdate = LocalDate.parse(sDate1,formatter);
sDate1 = formatter.format(lastdate);

但是我收到一个错误，因为无法在索引0处解析此文本'Thu Aug 06 00:00:00 TRT 2020'.

But i get an error as this Text 'Thu Aug 06 00:00:00 TRT 2020' could not be parsed at index 0.

所以这个圆锥体无法正常工作: LocalDate lastdate = LocalDate.parse(sDate1，formatter); 我看不出问题出在哪里.

So this cone not works fine : LocalDate lastdate = LocalDate.parse(sDate1,formatter); I cant see where is the problem.

推荐答案

代码失败的地方:

SimpleDateFormat sdf1=new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy");
String dateStr = "06.08.2020";
sdf1.parse(dateStr);

如您所见， SimpleDateFormat 的模式与 date 字符串的模式不匹配，因此，此代码将引发 ParseException .

As you can see, the pattern of the SimpleDateFormat and that of the date string do not match and therefore, this code will throw ParseException.

SimpleDateFormat sdf = new SimpleDateFormat("dd.MM.yyyy");
String dateStr = "06.08.2020";
Date date = sdf.parse(dateStr);

您必须已经知道它为什么起作用.之所以起作用，是因为 SimpleDateFormat 的模式与 dateStr 字符串的模式匹配.

You must have already got why it worked. It worked because the pattern of the SimpleDateFormat matches with that of the dateStr string.

是的，只需使用与解析原始字符串相同的格式，如下所示:

Yes, just use the same format which you used to parse the original string as shown below:

SimpleDateFormat sdf = new SimpleDateFormat("dd.MM.yyyy");
String dateStr = "06.08.2020";
Date date = sdf.parse(dateStr);

// Display in the default format
System.out.println(date);

// Format into the string
dateStr = sdf.format(date);
System.out.println(dateStr);

一条建议:

我建议您从过时且容易出错的 java.util 日期时间API和 SimpleDateFormat 切换到跟踪:日期时间 .

A piece of advice:

I recommend you switch from the outdated and error-prone java.util date-time API and SimpleDateFormat to the modern java.time date-time API and the corresponding formatting API (package, java.time.format). Learn more about the modern date-time API from Trail: Date Time.

使用现代的日期时间API:

Using the modern date-time API:

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd.MM.yyyy");
String dateStr = "06.08.2020";
LocalDate date = LocalDate.parse(dateStr, formatter);

// Display in the default format
System.out.println(date);

// Format into the string
dateStr = formatter.format(date);
System.out.println(dateStr);

使用旧版API和现代API没​​什么区别:

对于这个简单的示例来说确实如此，但是当您需要使用日期和时间执行复杂的操作时，您会发现现代的日期时间API既聪明又干净，而传统的API复杂且容易出错.

I don't see any difference using the legacy API and the modern API:

That's true for this simple example but when you will need to do complex operations using date and time, you will find the modern date-time API smart and clean while the legacy API complex and error-prone.

演示:

import java.time.LocalDateTime;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;

public class Main {
    public static void main(String[] args) {
        // Given date-time string
        String strDate = "Thu Aug 06 00:00:00 TRT 2020";

        // Replace TRT with standard time-zone string
        strDate = strDate.replace("TRT", "Europe/Istanbul");

        // Define formatter
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("EEE MMM dd HH:mm:ss zzzz yyyy");

        // Parse the date-time string into ZonedDateTime
        ZonedDateTime zdt = ZonedDateTime.parse(strDate, formatter);
        System.out.println(zdt);

        // If you wish, convert ZonedDateTime into LocalDateTime
        LocalDateTime ldt = zdt.toLocalDateTime();
        System.out.println(ldt);
    }
}

输出:

2020-08-06T00:00+03:00[Europe/Istanbul]
2020-08-06T00:00

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