How to convert date in to yyyy-MM-dd Format in Java

In this tutorial we are going learn about converting date format to yyyy-MM-dd Format in Java

A date (whether we’re talking java.util.Date or java.time.LocalDate) doesn’t have a format in it. All it’s got is a toString method that produces some format, and you cannot change the toString method. Fortunately, LocalDate.toString produces exactly the format you asked for.

The Date class is long outdated, and the SimpleDateFormat class that you tried to use, is notoriously troublesome. I recommend you forget about those classes and use java.time instead. The modern API is so much nicer to work with.

Except: it happens that you get a Date from a legacy API that you cannot change or don’t want to change just now. The best thing you can do with it is convert it to java.time.Instant and do any further operations from there:

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

public class BehindJava {
	public static void main(String[] args) {
		java.util.Date date = new Date("Sat Dec 01 00:00:00 GMT 2012");
		SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
		String format = formatter.format(date);
		System.out.println(format);

	}
}

Output:

2012-12-01

A date-time object is supposed to store the information about the date, time, timezone etc., not about the formatting. You can format a date-time object into a String with the pattern of your choice using date-time formatting API.

• The date-time formatting API for the modern date-time types is in the package, java.time.format e.g. java.time.format.DateTimeFormatter, java.time.format.DateTimeFormatterBuilder etc.
• The date-time formatting API for the legacy date-time types is in the package, java.text e.g. java.text.SimpleDateFormat, java.text.DateFormat etc.

Demo using modern API:

import java.time.LocalDate;
import java.time.Month;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        ZonedDateTime zdt = ZonedDateTime.of(LocalDate.of(2012, Month.DECEMBER, 1).atStartOfDay(),
                ZoneId.of("Europe/London"));

        // Default format returned by Date#toString
        System.out.println(zdt);

        // Custom format
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd", Locale.ENGLISH);
        String formattedDate = dtf.format(zdt);
        System.out.println(formattedDate);
    }
}

Output:

2012-12-01T00:00Z[Europe/London]
2012-12-01