Convert date value to string in java

Data Type Conversions in Java

In this tutorial, we will focus on type conversion for primitive data types.

String to int

There are two methods available for String to int conversion: Integer.parseInt() which returns a primitive int and Integer.valueOf() which return an Integer object.

String str = "1050"; int inum = Integer.parseInt(str); //return primitive System.out.println(inum); Integer onum = Integer.valueOf(str); //return object System.out.println(onum); 

String to long

Similar to int , we can convert a String into a primitive long value using Long.parseLong() or an object Long via Long.valueOf() method.

String longStr = "1456755"; long ilong = Long.parseLong(longStr); //return primitive System.out.println(ilong); Long olong = Long.valueOf(longStr); //return object System.out.println(olong); 

String to float

A String can be converted to primitive float value using Float.parseFloat() method. Float.valueOf() method can be used to convert a String into a Float object.

String floatStr = "49.78"; float ifloat = Float.parseFloat(floatStr); //return primitive System.out.println(ifloat); Float ofloat = Float.valueOf(floatStr); //return object System.out.println(ofloat); 

String to double

double and float data types may look same but are different in the way that they store the value. float is a single precision (32 bit or 4 bytes) floating point data type whereas double is a double precision (64 bit or 8 bytes) floating point data type.

A String value can be converted to double value using Double.parseDouble() method. Similarly, Double.valueOf() converts a String into a Double object.

String doubleStr = "99.378"; double idouble = Double.parseDouble(doubleStr); //return primitive System.out.println(idouble); Double odouble = Double.valueOf(doubleStr); //return object System.out.println(odouble); 

NumberFormatException

If the String does not contain a parsable value during int , float , or double conversion, a NumberFormatException is thrown.

try  String exeStr = "14c"; int exeInt = Integer.parseInt(exeStr); System.out.println(exeInt); > catch (NumberFormatException ex)  System.out.println(ex.getMessage()); > 

String to boolean

A String value can be converted to primitive boolean value using Boolean.parseBoolean method. For conversion to Boolean object, you can use Boolean.valueOf() method.

String trueStr = "true"; String falseStr = "false"; String randomStr = "java"; System.out.println(Boolean.parseBoolean(trueStr)); //true System.out.println(Boolean.valueOf(falseStr)); //false System.out.println(Boolean.parseBoolean(randomStr)); //false 

String to Date

Java provides SimpleDateFormat class for formatting and parsing dates. It has the following two important method:

• parse() — It converts a String value into a Date object
• format() — It converts the Date object into a String value

While creating an instance of the SimpleDateFormat classes, you need to pass date and time pattern that tells how the instance should parse or format the dates.

String dateStr = "10/03/2019"; SimpleDateFormat format = new SimpleDateFormat("dd/MM/yyyy"); Date dateObj = format.parse(dateStr); System.out.println(dateObj); 

In the example above, I used dd/MM/yyyy pattern to parse 10/03/2019 string. dd means two digits for the day, MM means two digit for the month and yyyy means 4 digits for the year. Below is a list of the most common date and time patterns used in SimpleDateFormat . For the complete list, please refer to official JavaDoc.

Letter	Description	Examples
y	Year	2019, 19
M	Month in year	March, Mar, 03, 3
d	Day in month	1-31
E	Date name in week	Friday-Sunday
a	Am/pm marker	AM, PM
H	Hour in day	0-23
h	Hour in am/pm	1-12
m	Minute in hour	0-59
s	Second in minute	0-59
S	Millisecond in second	0-999
z	General timezone	Central European Time, PST, GMT +05:00

Following are some pattern examples, with examples of how each pattern would parse a date or vice versa:

yyyy/MM/dd (2019/03/09) dd-MM-YYYY (10-03-2019) dd-MMM-yy (13-Feb-19) EEE, MMMM dd, yyy (Fri, March 09, 2019) yyyy-MM-dd HH:mm:ss (2019-02-28 16:45:23) hh:mm:ss a (11:23:36 PM) yyyy-MM-dd HH:mm:ss.SSS Z (2019-01-31 21:05:46.555 +0500) 

Date to String

As we discussed above, SimpleDateFormat also supports formatting of dates into strings. Here is an example that formats the date into a string:

Date date = Calendar.getInstance().getTime(); // OR new Date() SimpleDateFormat dateFormat = new SimpleDateFormat("EEEE, MMMM dd, yyyy HH:mm:ss.SSS Z"); String formatStr = dateFormat.format(date); System.out.println(formatStr); 

The above code snippet will print the following depending on your location:

Sunday, March 10, 2019 20:01:22.417 +0500 

Date to ISO 8601 String

ISO 8601 is an international standard that covers the exchange of date- and time-related data. There ere several ways to express date and time in ISO format:

2019-03-30T14:22:15+05:00 2019-03-30T09:22:15Z 20190330T092215Z 

Here is an example to convert a date object into an ISO 8601 equivalent string in Java:

TimeZone timeZone = TimeZone.getTimeZone("UTC"); SimpleDateFormat isoFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'"); isoFormat.setTimeZone(timeZone); String isoFormatStr = isoFormat.format(new Date()); System.out.println(isoFormatStr); 

Following are the date and time patterns for ISO format:

Pattern	ISO Date Format
yyyy-MM-dd’T’HH:mm:ssXXX	2019-03-30T14:22:15+05:00
yyyy-MM-dd’T’HH:mm:ss’Z’	2019-03-30T09:22:15Z
yyyyMMdd’T’HHmmss’Z’	20190330T092215Z

Source code: Download the complete source code from GitHub available under MIT license.

Conclusion

Data type conversions are very common for a developer. Most of these conversions are trivial and are well-known to an experienced programmer. However, string to date conversion is a bit tricky especially for beginners. You may encounter errors if the pattern is not specified correctly. But if you spend some time to remember these patterns, it may save a lot of time while figuring out why a certain conversion is not compiling or executing.

Am I missing any important type conversion in this tutorial? Send me a tweet any time to let me know.

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Convert Date to String in Java

1. Convert Date to String Using SimpleDateFormat in Java
2. Convert Date to String Using DateFormatUtils Class in Java
3. Convert Date to String Using DateTimeFormatter in Java
4. Convert Date to String With the Time Zone in Java
5. Convert Date to String With String Class in Java

This tutorial introduces how to convert java.util.Date to String in Java and lists some example codes to understand it.

Java has several classes and methods that help convert Date to String like using SimpleDateFormat , DateFormatUtils , and DateTimeFormatter class.

Convert Date to String Using SimpleDateFormat in Java

Here, We use format() method of SimpleDateFormat class to get String from the util.Date object in Java.

import java.text.DateFormat; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date;  public class SimpleTesting    public static void main(String[] args) throws ParseException   DateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");  Date date = new Date();  String dateToStr = dateFormat.format(date);  System.out.println("Date is "+ dateToStr);  > > 

Convert Date to String Using DateFormatUtils Class in Java

If you are using the Apache library then use format() method of DateFormateUtils class. It returns a string after converting java.util.Date to string in Java.

import java.text.ParseException; import java.util.Date; import org.apache.commons.lang3.time.DateFormatUtils;  public class SimpleTesting    public static void main(String[] args) throws ParseException   Date date = new Date();  String dateToStr = DateFormatUtils.format(date, "yyyy-MM-dd HH:mm:SS");  System.out.println("Date is "+ dateToStr);  > > 

Convert Date to String Using DateTimeFormatter in Java

Here, we use the format() method that takes the ofPattern() method as an argument and returns a string representation of a date. See the example below.

import java.text.ParseException; import java.time.ZoneOffset; import java.time.format.DateTimeFormatter; import java.util.Date;  public class SimpleTesting    public static void main(String[] args) throws ParseException   Date date = new Date();  String dateToStr = date.toInstant()  .atOffset(ZoneOffset.UTC)  .format( DateTimeFormatter.ofPattern("dd-MM-yyyy"));  System.out.println("Date is "+ dateToStr);  > > 

Convert Date to String With the Time Zone in Java

Here, we use format() method of the DateTimeFormatter class to get string after conversion from java.util.date . We get time zone along with date because we specified the date-time format in the ofPattern() method.

import java.text.ParseException; import java.time.ZoneId; import java.time.format.DateTimeFormatter; import java.util.Date;  public class SimpleTesting    public static void main(String[] args) throws ParseException   Date date = new Date();  DateTimeFormatter format = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss:SSS Z")  .withZone(ZoneId.systemDefault());  String dateToStr = format.format(date.toInstant());  System.out.println("Date is "+ dateToStr);  > > 

Date is 2020-09-21 09:10:23:991 +0530 

Convert Date to String With String Class in Java

This is one of the simplest solutions to get a String of java.util.date object. Here, we use the format() method of the String class that formats the date based on the specified format. See the example below.

import java.text.ParseException; import java.util.Date;  public class SimpleTesting    public static void main(String[] args) throws ParseException   Date date = new Date();  String dateToStr = String.format("%1$tY-%1$tm-%1$td", date);  System.out.println("Date is "+ dateToStr);  > > 

Related Article — Java String

Related Article — Java DateTime

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Convert date value to string in java

Let’s see the full example to convert date and time into String in java using format() method of java.text.SimpleDateFormat class.

Date Format with MM/dd/yyyy : 04/13/2015 Date Format with dd-M-yyyy hh:mm:ss : 13-4-2015 10:59:26 Date Format with dd MMMM yyyy : 13 April 2015 Date Format with dd MMMM yyyy zzzz : 13 April 2015 India Standard Time Date Format with E, dd MMM yyyy HH:mm:ss z : Mon, 13 Apr 2015 22:59:26 IST

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