Java LongStream average() Method

The average() method in Java, part of the java.util.stream.LongStream interface, is used to calculate the average of the elements in the stream. This method is useful when you need to compute the mean value of a sequence of long values.

Table of Contents

1. Introduction
2. average() Method Syntax
3. Understanding average()
4. Examples
   • Basic Usage
   • Using average() in Combination with Other Stream Operations
5. Real-World Use Case
6. Conclusion

Introduction

The average() method is a terminal operation that calculates the average of the elements in the stream. The method returns an OptionalDouble, which will be empty if the stream is empty.

average() Method Syntax

The syntax for the average() method is as follows:

OptionalDouble average()

Parameters:

• This method does not take any parameters.

Returns:

• An OptionalDouble describing the average of the elements in the stream, or an empty OptionalDouble if the stream is empty.

Throws:

• This method does not throw any exceptions.

Understanding average()

The average() method computes the average of all elements in the stream. If the stream is empty, the method returns an empty OptionalDouble. Otherwise, it returns an OptionalDouble containing the average value.

Examples

Basic Usage

To demonstrate the basic usage of average(), we will create a LongStream and calculate the average of its elements.

Example

import java.util.OptionalDouble;
import java.util.stream.LongStream;

public class AverageExample {
    public static void main(String[] args) {
        LongStream stream = LongStream.of(1L, 2L, 3L, 4L, 5L);

        // Use average() to calculate the average of the elements
        OptionalDouble average = stream.average();

        // Print the average if present
        average.ifPresent(System.out::println);
    }
}

Output:

3.0

Using average() in Combination with Other Stream Operations

This example shows how to use average() in combination with other stream operations, such as filtering.

Example

import java.util.OptionalDouble;
import java.util.stream.LongStream;

public class AverageWithFilterExample {
    public static void main(String[] args) {
        LongStream stream = LongStream.of(10L, 20L, 30L, 40L, 50L);

        // Use average() to calculate the average of the filtered elements
        OptionalDouble average = stream.filter(n -> n > 20).average();

        // Print the average if present
        average.ifPresent(System.out::println);
    }
}

Output:

40.0

Real-World Use Case

Calculating Average Transaction Amount

In real-world applications, the average() method can be used to calculate the average amount of transactions from a stream of transaction values.

Example

import java.util.OptionalDouble;
import java.util.stream.LongStream;

public class AverageTransactionExample {
    public static void main(String[] args) {
        LongStream transactionAmounts = LongStream.of(1000L, 2000L, 1500L, 3000L, 2500L);

        // Use average() to calculate the average transaction amount
        OptionalDouble average = transactionAmounts.average();

        // Print the average transaction amount if present
        average.ifPresent(amount -> System.out.println("Average Transaction Amount: " + amount));
    }
}

Output:

Average Transaction Amount: 2000.0

Conclusion

The LongStream.average() method is used to calculate the average of the elements in the stream. This method is particularly useful for computing the mean value of a sequence of long values. By understanding and using this method, you can efficiently manage and process streams of values in your Java applications, ensuring accurate calculations of averages.