How to convert String to Date in Java - SimpleDateFormat Example

Hello Java developers, you may know that SimpleDateFormat in Java can be used to convert String to Date in Java. java.text.SimpleDateFormat is an implementation of DateFormat which defines a date pattern and can convert a particular String that follows that pattern into Date in Java. This is the second part of the article on java.util.Date and String in Java. In the first part, we have seen How to convert Date to String in Java. SimpleDateFormat accepts a String in any date format e.g. yyyyMMdd is a date pattern and  20220924 is a String in that format. Now you want to create a java.util.Date object from this String.

In this Java tutorial, we will see a list of steps to convert String to Date in Java, and then we will see different examples of SimpleDateFormat with different date patterns e.g. ddMMyy or dd-MM-yyyy. 

Though converting String to Date is quite easy using SimpleDateFormat, but you need to remember that SimpleDateFormat is not thread-safe, which means you can not share the same instance of SimpleDateFormat between multiple threads. 

Avoid storing SimpleDateFormat in a static variable and if you want to safely share or reuse SimpleDateFormat, you need to make it thread-safe. One way is to use the ThreadLocal variable in Java to make SimpleDateFormat thread-safe, as shown in this example.

By the way, if you are using Java 8 and beyond like Java 11 or Java 17 then I highly recommend you to use LocalDate and LocalTime in Java. Both LocalDate and LocalTime are easier to format and parse using DatFormatter class which provides many common built-in formatter like ISO date format and YYYYMMDD format as well local dat formats. 

All these makes converting String to LocalDate really easy. They are also Immutable and thread-safe which means you can use them in your multithreading application without worrying about synchronization and Locking. 

Steps to Convert String to Date in Java with Example

Converting String to date is rather a common scenario because you may get a date in a String format from any file or xml document. SimpleDateFormat in Java also supports time information e.g. HH for an hour, mm for minutes, and SS for seconds.

Here are steps we need to use for conversion in Java:

1. Create a SimpleDateFormat object with a date pattern e.g. dd-MM-yyyy. here d denotes the day of the month, M is for the month of year and yyyy is the year in four-digit like 2022. Java documentation of SimpleDateFormat has a complete list of date and time patterns specified.

2. Call parse() method of SimpleDateFormat and cast the result into Date object and you are done. parse() method of SimpleDateFormat throws ParseException so you need to either throw it or you can provide handling of this exception. 

Let’s see some SimpleDateFormat Examples of converting a string to date in Java to get hold of the concept.  

     

String to Date using SimpleDateFormat Example in Java

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


/**
 * Java program to convert String to Date in Java. This example
 * use SimpleDateFormat for String to Date conversion, you can also
 * use JODA date and time API for that.
 *
 * @author Javin
 */
public class StringToDateExample{
   
   public static void main(String args[]) throws ParseException{
       
        DateFormat formatter = null;
        Date convertedDate = null;
       
       // Creating SimpleDateFormat with yyyyMMdd format e.g."20220914"
        String yyyyMMdd = "20220914";
        formatter =new SimpleDateFormat("yyyyMMdd");
        convertedDate =(Date) formatter.parse(yyyyMMdd);
        System.out.println("Date from yyyyMMdd String in Java : " + convertedDate);

       //convert string to date with ddMMyyyy format example "14092022"
        String ddMMyyyy = "14092022";
        formatter =new SimpleDateFormat("ddMMyyyy");
        convertedDate =(Date) formatter.parse(ddMMyyyy);
        System.out.println("Date from ddMMyyyy String in Java : " + convertedDate);

       //String to Date conversion in Java with dd-MM-yyyy format e.g. "14-09-2022"
        String dd_MM_YY = "14-09-2022";
        formatter =new SimpleDateFormat("dd-MM-yyyy");
        convertedDate =(Date) formatter.parse(dd_MM_YY);
        System.out.println("Date from dd-MM-yyyy String in Java : " + convertedDate);

       // dd/MM/yyyy date format for example "14/09/2022"
        String stringDateFormat = "14/09/2022";
        formatter =new SimpleDateFormat("dd/MM/yyyy");
        convertedDate =(Date) formatter.parse(stringDateFormat);
        System.out.println("Date from dd/MM/yyyy String in Java : " + convertedDate);

       //parsing string into date with dd-MMM-yy format e.g. "14-Sep-11"
       //MMMM denotes three letter month String e.g. Sep
        String ddMMMyy = "14-Sep-11";
        formatter =new SimpleDateFormat("dd-MMM-yy");
        convertedDate =(Date) formatter.parse(ddMMMyy);
        System.out.println("Date from dd-MMM-yy String in Java : " + convertedDate);

       //convert string to Date of dd-MMMM-yy format e.g. "14-September-11"
       //MMMM denotes full month String e.g. September
        String dMMMMyy = "14-September-11";
        formatter =new SimpleDateFormat("dd-MMMM-yy");
        convertedDate =(Date) formatter.parse(dMMMMyy);
        System.out.println("Date from dd-MMMM-yy String in Java : " + convertedDate);
       
       //SimpleDateFormat also allows to include time information e.g. dd-MM-yyyy:HH:mm:SS
        String date = "15-09-2022:23:30:45";
        formatter =new SimpleDateFormat("dd-MM-yyyy:HH:mm:SS");
        convertedDate =(Date) formatter.parse(date);
        System.out.println("Date from dd-MM-yyyy:HH:mm:SS String in Java : " 

                            + convertedDate);
   }
}

Output:
Date from yyyyMMdd String in Java : Wed Sep 14 00:00:00 PST 2022
Date from ddMMyyyy String in Java : Wed Sep 14 00:00:00 PST 2022
Date from dd-MM-yyyy String in Java : Wed Sep 14 00:00:00 PST 2022
Date from dd/MM/yyyy String in Java : Wed Sep 14 00:00:00 PST 2022
Date from dd-MMM-yy String in Java : Wed Sep 14 00:00:00 PST 2022
Date from dd-MMMM-yy String in Java : Wed Sep 14 00:00:00 PST 2022
Date from dd-MM-yyyy:HH:mm:SS String in Java : Thu Sep 15 23:30:00 PST 2022

You can check the java doc of DateFormat for all the symbols it supports and what is meaning for that but here I am listing some common points which are worth remembering while working with SimpleDateFormat for conversion.

1. Confusion between “m” and “M”, small case “m” represent minutes while “M” represents Month Also “d” represent a date in a month while “D” represent Day of the week. This is the most common cause of error while converting String to date and backdate to a string. In short, ddMMyy is not equal to DDmmyy.

2. SimpleDateFormat is not thread-safe. They are not synchronized so it's better you create separate SimpleDateFormat for each thread to avoid any race condition while parsing.

That's all about how to convert String to Date in Java. Java is very rich in terms of date-time support and it also provides a convenient way to convert string to date which is very handy while working in Java applications. 

Though, I highly recommend you to switch to new Date and Time API from Java 8 which provides both Immutable and thread-safe LocalDate and LocalTime objects. They also provide utilities like DateTimeFormatter which can easily convert String to LocalDate and LocalDate to String in Java. 

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