How to Convert Local Time to GMT in Java?

04 Jul, 2021
Time conversion from IST or any standard time to GMT is necessary for locals to understand and reciprocate their international clients if they are connected overseas in terms of work or any purpose. Today we will have a look at a code where we convert the standard time of any country to GMT. 
Here we would use the SimpleDateFormat to convert the local Time in GMT. It is available in class as mentioned:
java.util.SimpleDateFormat
Methods: One can use different methods like SimpleDateFormat or maybe even Instance() method. They are very easy and helpful methods. We can also use calendar and time methods to do so.
Using format() method of SimpleDateFormat classUsing instance() method of SimpleDateFormat class
Using format() method of SimpleDateFormat class
Using instance() method of SimpleDateFormat class
Method 1: Using format() method of SimpleDateFormat class
The format() method of DateFormat class in Java is used to format a given date into a Date/Time string. Basically, the method is used to convert this date and time into a particular format i.e., mm/dd/yyyy.
Syntax:
public final String format(Date date)
Parameters: The method takes one parameter date of Date object type and refers to the date whose string output is to be produced.
Return Value: The method returns Date or time in string format of mm/dd/yyyy.
Procedure:
Here we would simply first print our local time
Then convert it to GMT using SimpleDateFormat
Then print both the time zones.
Example:
Java
// Java Program to convert local time to GMT // Importing libraries// 1. input output librariesimport java.io.*;// 3. Text classimport java.text.DateFormat;import java.text.SimpleDateFormat;// 2. Utility libraries for// Date and TimeZone classimport java.util.Date;import java.util.TimeZone; // Classclass GFG {     // Main driver method    public static void main(String[] args)    {         // Creating a Date class object        // to take local time from the user        Date localTime = new Date();         // Creating a DateFormat class object to        // convert the localtime to GMT        DateFormat s = new SimpleDateFormat("dd/MM/yyyy"                                            + " "                                            + " HH:mm:ss");         //  function will helps to get the GMT Timezone        // using the getTimeZOne() method        s.setTimeZone(TimeZone.getTimeZone("GMT"));         // One can get any other time zone also        // by passing some other argument to it         // Printing the local time        System.out.println("local Time:" + localTime);         // Printing the GMT time to        // illustrate changes in GMT time        System.out.println("Time IN Gmt : "                           + s.format(localTime));    }}
  
local Time:Thu Feb 04 11:34:15 UTC 2021
Time IN Gmt : 04/02/2021  11:34:15
 
Method 2: Using instance() method of SimpleDateFormat class
 
As in the above method we used SimpleDateFormat, we will now use the instant method to get the time. The SimpleDateFormat can be used in different ways, now the instant method can be used to get the UTC or GMT.
 
Procedure:
 
We will use the Instant method to get the time proper time
It can be importing the complete time class
 java.time.* ;
 
Example:
 
Java
// Java Program to convert Local time to// GMT time // Importing all input output classesimport java.io.*;// Importing all time classesimport java.time.*; // Classclass GFG {     // Main driver method    public static void main(String[] args)    {         // Instant operator helps to note        // the time and the location of it         // Creating an object of Instant type        // using the now() method        Instant now = Instant.now();         // Now with the help of Instant operator        // zoned operator is called         // Creating an object of ZonedDateTime        ZonedDateTime zdt = ZonedDateTime.ofInstant(            now, ZoneId.systemDefault());         // Printing the local time        System.out.println(" Local : " + zdt);         // Creating an object of  Instant type        // taking any other instant method        Instant instant = Instant.now();         // Printing the GMT/UTC time by parsing with string        // using the toString() method        System.out.println(" GMT : "+instant.toString());    }}
  
 Local : 2021-02-04T10:40:34.436700Z[Etc/UTC]
 GMT : 2021-02-04T10:40:34.547680Z
 
simmytarika5
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