Java String to Date object of the format “yyyy-mm-

2020-02-27 05:53发布

问题:

I need to convert a String containing date into an date object. The String will be of the format "yyyy-mm-dd HH:mm:ss.SSSSSS" and I want the same format in an date object.

For instance I have a string "2012-07-10 14:58:00.000000", and I need the resultant date object to be of the same format.

I have tried the below methods but, the resultant is not as expected.

java.util.Date temp = new SimpleDateFormat("yyyy-mm-dd HH:mm:ss.SSSSSS").parse("2012-07-10 14:58:00.000000");

DateFormat dateFormat = new SimpleDateFormat("yyyy-mm-dd HH:mm:ss");
                Date thisDate = dateFormat.parse("2012-07-10 14:58:00.000000");

The result is "Tue Jan 10 14:58:00 EST 2012". Please let me know where I am going wrong.

Thanks, Yeshwanth Kota

回答1:

java.util.Date temp = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSSSS").parse("2012-07-10 14:58:00.000000");

The mm is minutes you want MM

CODE

public class Test {

    public static void main(String[] args) throws ParseException {
        java.util.Date temp = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSSSS")
                .parse("2012-07-10 14:58:00.000000");
        System.out.println(temp);
    }
}

Prints:

Tue Jul 10 14:58:00 EDT 2012



回答2:

For future reference:

 yyyy => 4 digit year
 MM   => 2 digit month (you must type MM in ALL CAPS)
 dd   => 2 digit "day of the month"

 HH   => 2-digit "hour in day" (0 to 23)
 mm   => 2-digit minute (you must type mm in lowercase)
 ss   => 2-digit seconds
 SSS  => milliseconds

So "yyyy-MM-dd HH:mm:ss" returns "2018-01-05 09:49:32"

But "MMM dd, yyyy hh:mm a" returns "Jan 05, 2018 09:49 am"

The so-called examples at https://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html show only output. They do not tell you what formats to use!



回答3:

tl;dr

LocalDateTime.parse( 
    "2012-07-10 14:58:00.000000".replace( " " , "T" )  
)

Microseconds do not fit

You are attempting to squeeze a value with microseconds (six decimal digits) into a data type capable only of milliseconds resolution (three decimal digits). That is impossible.

Instead, use a data type with fine enough resolution. The java.time classes use nanosecond resolution (nine decimal digits).

Unzoned input does not fit a zoned type

You are attempting to put a value lacking any offset-from-UTC or time zone into a data type (Date) that only represents values in UTC. So you are adding information (UTC offset) not intended by the input.

Use an appropriate data type instead. Specifically, java.time.LocalDateTime.

Case-sensitive

Other Answers and Comments correctly explain that the formatting pattern codes are case-sensitive. So MM and mm have different effects.

Avoid legacy classes

The troublesome old date-time classes bundled with the earliest versions of Java are now legacy, supplanted by the java.time classes built into Java 8 and later.

ISO 8601

Your input strings nearly comply with the ISO 8601 standard formats. Replace the SPACE in the middle with a T to comply fully.

The java.time classes use the standard formats by default when parsing/generating strings. So no need to specify a formatting pattern.

Date-time objects have no "format"

and I need the resultant date object to be of the same format.

No, date-time objects do not have a "format". Do not conflate date-time objects with mere strings. Strings are inputs and outputs of the objects. The objects maintain their own internal representions of the date-time info, the details of which are irrelevant to us as calling programmers.

java.time

Your input lacks any indicator of offset-from-UTC or troublesome me zone. So we parse as a LocalDateTime objects which lacks those concepts.

String input = "2012-07-10 14:58:00.000000".replace( " " , "T" ) ;
LocalDateTime ldt = LocalDateTime.parse( input ) ;

Generating strings

To generate a String representing the value of your LocalDateTime:

  • Call toString to get a String in standard ISO 8601 format.
  • Use DateTimeFormatter for producing strings in either custom formats or automatically-localized formats.

Search Stack Overflow for more info as these topics have been covered many many times already.

ZonedDateTime

A LocalDateTime does not represent an exact point on the timeline.

To determine an actual moment, assign a time zone. For example noon in Kolkata India comes much earlier than noon in Paris France. Noon without a time zone could be happening at any point over a range of about 26-27 hours.

ZoneId z = ZoneId.of( "Asia/Kolkata" ) ;
ZonedDateTime zdt = ldt.atZone( z ) ;

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

  • Java SE 8, Java SE 9, and later
    • Built-in.
    • Part of the standard Java API with a bundled implementation.
    • Java 9 adds some minor features and fixes.
  • Java SE 6 and Java SE 7
    • Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
  • Android
    • Later versions of Android bundle implementations of the java.time classes.
    • For earlier Android, the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.



回答4:

Your not applying Date formator. rather you are just parsing the date. to get output in this format

yyyy-MM-dd HH:mm:ss.SSSSSS

we have to use format() method here is full example:- Here is full example:- it will take Date in this format yyyy-MM-dd HH:mm:ss.SSSSSS and as result we will get output as same as this format yyyy-MM-dd HH:mm:ss.SSSSSS

 import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

//TODO OutPut should LIKE in this format yyyy-MM-dd HH:mm:ss.SSSSSS.
public class TestDateExample {

public static void main(String args[]) throws ParseException {

    SimpleDateFormat changeFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSSSS");

    java.util.Date temp = changeFormat.parse("2012-07-10 14:58:00.000000");
     Date thisDate = changeFormat.parse("2012-07-10 14:58:00.000000");  
    System.out.println(thisDate);
    System.out.println("----------------------------"); 
    System.out.println("After applying formating :");
    String strDateOutput = changeFormat.format(temp);
    System.out.println(strDateOutput);

}

}



回答5:

its work for me SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); sdf.format(new Date));