Java LocalDateTime minusHours()

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In this guide, you will learn about the LocalDateTime minusHours() method in Java programming and how to use it with an example.

1. LocalDateTime minusHours() Method Overview

Definition:

The LocalDateTime.minusHours() method returns a copy of the LocalDateTime with the specified number of hours subtracted.

Syntax:

LocalDateTime minusHours(long hours)

Parameters:

- hours: The number of hours to subtract, may be negative.

Key Points:

- The LocalDateTime.minusHours() method is useful for date and time arithmetic where you want to manipulate the hour part of a LocalDateTime.

- The returned LocalDateTime instance is immutable, which means the original LocalDateTime instance remains unchanged.

- If subtracting the hours results in a date-time before the minimum date (LocalDateTime.MIN), a DateTimeException will be thrown.

- Subtracting a negative value is the same as adding the absolute value of that number of hours.

2. LocalDateTime minusHours() Method Example

import java.time.LocalDateTime;

public class LocalDateTimeMinusHoursExample {
    public static void main(String[] args) {
        LocalDateTime dateTime = LocalDateTime.of(2023, 1, 1, 0, 0);

        // Subtract 1 hour from the LocalDateTime
        LocalDateTime result1 = dateTime.minusHours(1);

        // Add 3 hours by subtracting a negative value
        LocalDateTime result2 = dateTime.minusHours(-3);

        System.out.println("Original DateTime: " + dateTime);
        System.out.println("After subtracting 1 hour: " + result1);
        System.out.println("After adding 3 hours: " + result2);
    }
}

Output:

Original DateTime: 2023-01-01T00:00
After subtracting 1 hour: 2022-12-31T23:00
After adding 3 hours: 2023-01-01T03:00

Explanation:

In the example, we have a LocalDateTime set to January 1, 2023, at midnight (00:00).

- When we subtract 1 hour using minusHours(1), the time becomes 23:00 on December 31, 2022, demonstrating the method's capability to handle day, month, and year boundaries.

- When we add 3 hours using minusHours(-3), the time becomes 03:00 on January 1, 2023.