The average()
method in Java, part of the java.util.stream.DoubleStream
interface, is used to calculate the average of the elements in a stream. This method is useful when you need to compute the average value of a sequence of double values.
Table of Contents
- Introduction
average()
Method Syntax- Understanding
average()
- Examples
- Basic Usage
- Handling an Empty Stream
- Real-World Use Case
- Conclusion
Introduction
The average()
method returns an OptionalDouble
describing the arithmetic mean of the elements of the stream, or an empty OptionalDouble
if the stream is empty. This is a terminal operation.
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
containing the average value of the elements of the stream, or an emptyOptionalDouble
if the stream is empty.
Throws:
- This method does not throw any exceptions.
Understanding average()
The average()
method computes the average value of all elements in a DoubleStream
. If the stream is empty, it returns an empty OptionalDouble
, which can be checked to determine if a value is present.
Examples
Basic Usage
To demonstrate the basic usage of average()
, we will create a DoubleStream
and calculate the average of its elements.
Example
import java.util.OptionalDouble;
import java.util.stream.DoubleStream;
public class AverageExample {
public static void main(String[] args) {
DoubleStream numbers = DoubleStream.of(1.1, 2.2, 3.3, 4.4, 5.5);
// Calculate the average of the numbers
OptionalDouble average = numbers.average();
average.ifPresent(avg -> System.out.println("Average: " + avg));
}
}
Output:
Average: 3.3
Handling an Empty Stream
This example shows how to handle an empty stream when using the average()
method.
Example
import java.util.OptionalDouble;
import java.util.stream.DoubleStream;
public class EmptyStreamExample {
public static void main(String[] args) {
DoubleStream emptyStream = DoubleStream.empty();
// Calculate the average of the empty stream
OptionalDouble average = emptyStream.average();
if (average.isPresent()) {
System.out.println("Average: " + average.getAsDouble());
} else {
System.out.println("The stream is empty, no average value.");
}
}
}
Output:
The stream is empty, no average value.
Real-World Use Case
Calculating Average Temperature
In real-world applications, the average()
method can be used to calculate the average temperature from a list of temperature readings.
Example
import java.util.OptionalDouble;
import java.util.stream.DoubleStream;
public class TemperatureAverageExample {
public static void main(String[] args) {
DoubleStream temperatures = DoubleStream.of(36.5, 37.0, 36.8, 37.1, 36.9);
// Calculate the average temperature
OptionalDouble averageTemperature = temperatures.average();
averageTemperature.ifPresent(avg -> System.out.println("Average Temperature: " + avg));
}
}
Output:
Average Temperature: 36.86
Conclusion
The DoubleStream.average()
method is used to calculate the average of the elements in a stream. This method is particularly useful for computing the average value of a sequence of double values. By understanding and using this method, you can efficiently perform average calculations on streams of double values in your Java applications.
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