Can we change Default time provide by spring in SimpleDateFormat

Question

    this.mdbReading.y = new Date[reading.y.length];
    SimpleDateFormat ydateFormat = new SimpleDateFormat("yyyy-MM-dd");
    
    for ( i = 0; i < reading.y.length; i++) {    
        //System.out.println("i = " + i + " string is "+ reading.y[i]);                                   
        try {
            
            this.mdbReading.y[i] = ydateFormat.parse(reading.y[i]);
        } catch (Exception e) {
            //TODO: handle exception
            System.out.println("Exception in date parse "+ e);
            break;
        }
    }

This is my code,where input string i.e reading.y[i] is in this format "2016-04-28" ..I am getting output as "2016-04-24 T18.30:00 00:00:00" while I am expecting output as "2016-04-24 T00.000:00 00:00:00" ..so is there any way to set the default time to 00:00?

I recommend you don’t use `SimpleDateFormat` and `Date`. Those classes are poorly designed and long outdated, the former in particular notoriously troublesome. Instead use `LocalDate` and `DateTimeFormatter`, both from [java.time, the modern Java date and time API](https://docs.oracle.com/javase/tutorial/datetime/). See the answer. — Ole V.V., Oct 25 '21 at 07:12
[Anti-pattern: parallel collections](https://codeblog.jonskeet.uk/2014/06/03/anti-pattern-parallel-collections/). You haven’t posted complete code, so it’s hard to be sure. I think I smell a poor design. If so, the link should help. — Ole V.V., Oct 25 '21 at 07:15

Arvind Kumar Avinash · Answer 1 · 2021-10-23T12:00:14.080

java.time

The java.util Date-Time API and their formatting API, SimpleDateFormat are outdated and error-prone. It is recommended to stop using them completely and switch to the modern Date-Time API^*.

Solution using java.time, the modern Date-Time API:

import java.text.ParseException;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;

public class Main {
    public static void main(String[] args) throws ParseException {
        LocalDate date = LocalDate.parse("2016-04-28");
        System.out.println(date);

        // In case you also need time-part as 00:00
        LocalDateTime ldt = date.atTime(LocalTime.MIN);
        System.out.println(ldt);
    }
}

Output:

2016-04-28
2016-04-28T00:00

The modern Date-Time API is based on ISO 8601 and does not require using a DateTimeFormatter object explicitly as long as the Date-Time string conforms to the ISO 8601 standards. Your date string is already in the ISO 8601 format.

Learn more about the modern Date-Time API from Trail: Date Time. Check this answer and this answer to learn how to use java.time API with JDBC.

What went wrong with your code?

By default SimpleDateFormat uses the default timezone while parsing any string. Given below is the code to reproduce your error:

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

public class Main {
    public static void main(String[] args) throws ParseException {
        TimeZone.setDefault(TimeZone.getTimeZone("Asia/Kolkata"));
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        System.out.println(sdf.parse("2016-04-28").toInstant());
    }
}

Output:

2016-04-27T18:30:00Z

In order to keep the time part 00:00:00, you need to set UTC timezone to the SimpleDateFormat instance.

Demo:

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

public class Main {
    public static void main(String[] args) throws ParseException {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
        System.out.println(sdf.parse("2016-04-28").toInstant());
    }
}

Output:

2016-04-28T00:00:00Z

^{* If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring. Note that Android 8.0 Oreo already provides support for java.time.}

Can we change Default time provide by spring in SimpleDateFormat

1 Answers1

java.time

What went wrong with your code?