simpledate formater to format returns incorrect.deducted date after formating [duplicate]

问题

This question already has answers here:

SimpleDateFormat producing wrong date time when parsing “YYYY-MM-dd HH:mm” (5 answers)

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Unable to parse date Apr 15, 2020 12:14:17 AM to LocalDatetime (2 answers)

Closed 4 months ago.

I am attempting to parse date using SimpleDateFormat. The date is parsed successfully but the output date format is incorrect or deducted by a year, The Date method that uses SimpleDateFormat is shown below

public Date parseDate(String date) {
        SimpleDateFormat format = new SimpleDateFormat("YYYY-MM-DD",Locale.ENGLISH);
        Date parsedDate = null;
        try {
            parsedDate = format.parse(date);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return parsedDate;
    }

Here is the sample image parsed

Date start = parseDate(dateVal); // dateVal sample is 2020-09-25

When the date is parsed, this is the output

Sun Dec 29 00:00:00 WAT 2019 

My challenge is to return a date sample of - 2020-09-25 after parsing

回答1:

You have used the wrong symbols. Use yyyy-MM-dd instead of YYYY-MM-DD. Note that DD stands for the Day of the year and Y stands for Week year. Check the documentation to learn more about it.

Also, I recommend you switch from the outdated and error-prone java.util date-time API and SimpleDateFormat to the modern java.time date-time API and the corresponding formatting API (package,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.

If you are using Android and your Android API level is still not compliant with Java8, check How to use ThreeTenABP in Android Project and Java 8+ APIs available through desugaring.

Using modern date-time API:

import java.time.LocalDate;

public class Main {
    public static void main(String[] args) {
        LocalDate date = LocalDate.parse("2020-09-25");
        System.out.println(date);
    }
}

Output:

2020-09-25

Note that since your date-time string is already in the ISO8601 format, you do not need to use any DateTimeFormatter while parsing it to LocalDate as it is the default pattern used by LocalDate#parse.

Using the legacy date-time API:

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

public class Main {
    public static void main(String[] args) throws ParseException {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        Date date = sdf.parse("2020-09-25");
        System.out.println(date);
    }
}

回答2:

You can do it like so:

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd", Locale.ENGLISH);
format.setTimeZone(TimeZone.getTimeZone("UTC"));
parsedDate = format.parse(date);

You should be using parse(String) instead of parseDate()

来源：https://stackoverflow.com/questions/64071686/simpledate-formater-to-format-returns-incorrect-deducted-date-after-formating