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.

1. package java8;
2. /**
3.  * By: www.instanceofjava.com
4.  * program: how to subtract hours from date time using java 8  
5. *
6.  */
7. import java.time.LocalDateTime;
8. import java.time.format.DateTimeFormatter;
9.  
10. public class SubstractHoursJava{
12. public static void main(String[] args) {
13.  
14.   DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
15.  
16.         String currentTime= "2017-10-19 22:00:00";
18.  
19.         System.out.println("Before subtraction of hours from date: "+currentTime);
20.  
21.         LocalDateTime datetime = LocalDateTime.parse(currentTime,formatter);
22.  
23.         datetime=datetime.minusHours(4);
24.  
25.         String aftersubtraction=datetime.format(formatter);
26.         System.out.println("After 4 hours subtraction from date: "+aftersubtraction);
28.  
29.     }
30.  
31. }

Output:

1. Before subtraction of hours from date: 2017-10-19 22:00:00
2. After 4 hours subtraction from date: 2017-10-19 18:00:00

• 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.

1. package java8;
2. /**
3.  * By: www.instanceofjava.com
4.  * program: how to subtract hours from date time using java 8  
5. *
6.  */
7. import java.time.LocalDateTime;
8. import java.time.format.DateTimeFormatter;
9.  
10. public class SubtractOneHour {
11.  
12. public static void main(String[] args) {
13.  
14.   DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd H:mm:ss");
15.  
16.         LocalDateTime datetime = LocalDateTime.now();
17.         System.out.println("Before subtraction of hours from date: "+datetime.format(formatter));
19.  
20.        datetime=datetime.minusHours(1);
21.        String aftersubtraction=datetime.format(formatter);
22.        System.out.println("After 1 hour subtraction from date: "+aftersubtraction);
24.  
25.     }
26.  
27. }

Output:

1. Before subtraction of hours from date: 2017-10-19 23:14:12
2. After 1 hour subtraction from date: 2017-10-19 22:14:12