Java 8 Streams - LongStream.average Examples

[Last Updated: Nov 8, 2025]

Interface:

java.util.stream.LongStream

Method:

OptionalDouble average()

This terminal operation returns an OptionalDouble describing the arithmetic mean of elements of this stream, or an empty optional if this stream is empty. This is a special case of reduction.

Examples

Using LongStream#average method:

package com.logicbig.example;

import java.util.stream.LongStream;

public class AverageExample {
    public static void main (String[] args) {
        double v = LongStream.range(1, 10).average().orElse(-1);
        System.out.println(v);
    }
}

Output

5.0

Original Post

package com.logicbig.example.longstream;

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

public class AverageExample {

    public static void main(String... args) {
        LongStream stream = LongStream.of(3, 6, 9);
        OptionalDouble average = stream.average();
        double v = average.orElseGet(() -> -1d);
        System.out.println(v);
    }
}

Output

6.0

Java 8 Streams - LongStream.average Examples

Interface:

Method:

Examples

Output

Output

See Also