Java Buzz Forum - How to subtract N hours from current date time using java 8

We have already seen how to subtract number of days from java using calendar and using java 8.
How to subtract X days from a date using Java calendar and with java 8
Now we will discuss here how to subtract hours from java 8 localdatetime.
Some times we will get out date time in string format so we will convert our string format date to java 8 LocaDateTime object.
We can user DateTimeFormatter to tell the format of date time to LocalDateTime class.
LocalDateTime datetime = LocalDateTime.parse(currentTime,formatter);
LocalDateTime has minusHours(numberOfHours) method to subtract hours from date time.
Lets see an example java program to subtract hours from java date time using java 8 LocalDateTime class.
How to subtract hours from java 8 date time.

Program #1 : Java Example Program to subtract hours from given string formatted date time using java 8.

package java8;
/**
* By: www.instanceofjava.com
* program: how to subtract hours from date time using java 8
*
*/
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class SubstractHoursJava{
public static void main(String[] args) {
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
String currentTime= "2017-10-19 22:00:00";
System.out.println("Before subtraction of hours from date: "+currentTime);
LocalDateTime datetime = LocalDateTime.parse(currentTime,formatter);
datetime=datetime.minusHours(4);
String aftersubtraction=datetime.format(formatter);
System.out.println("After 4 hours subtraction from date: "+aftersubtraction);
}
}

Output:

Now we will see how to subtract one hour from current date time in java using java 8

Program #2 : Java Example Program to subtract one hour from given current date time using java 8.

package java8;
/**
* By: www.instanceofjava.com
* program: how to subtract hours from date time using java 8
*
*/
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class SubtractOneHour {
public static void main(String[] args) {
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd H:mm:ss");
LocalDateTime datetime = LocalDateTime.now();
System.out.println("Before subtraction of hours from date: "+datetime.format(formatter));
datetime=datetime.minusHours(1);
String aftersubtraction=datetime.format(formatter);
System.out.println("After 1 hour subtraction from date: "+aftersubtraction);
}
}

Output:


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