# Calculate average of doubles using Lambda expression in Java

## Java Lambda Program: Exercise-6 with Solution

Write a Java program to implement a lambda expression to find the average of a list of doubles.

Sample Solution:

Java Code:

``````import java.util.Arrays;
import java.util.List;

public class Main {
public static void main(String[] args) {
// Create a list of doubles
List<Double> nums = Arrays.asList(3.5, 7.5, 4.3, 4.7, 5.1);
// Print the list elements
System.out.println("Original values: " + nums);

// Calculate the average of the list using lambda expression
double average = nums.stream()
.mapToDouble(Double::doubleValue)
.average()
.orElse(0.0);

// Print the average
System.out.println("\nAverage of the original values: " + average);
}
}
``````

Sample Output:

```Original values: [3.5, 7.5, 4.3, 4.7, 5.1]

Average of the original values: 5.0200000000000005
```

Explanation:

To calculate the average of the list, we use the stream() method on the nums list to convert it into a stream. Then, we use the mapToDouble() method to convert each Double object to its corresponding primitive double value. This step is necessary because the average() method operates on primitive double values.

Next, we call the average() method to calculate the average of the stream. If the stream is empty, we use orElse(0.0) to provide a default value of 0.0.

Flowchart:

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Java Lambda Exercises Previous: Sort strings in alphabetical order using Lambda expression in Java.
Java Lambda Exercises Next: Remove duplicates from list of integers using Lambda expression in Java.

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## Java: Tips of the Day

How do I remove repeated elements from ArrayList?

If you don't want duplicates in a Collection, you should consider why you're using a Collection that allows duplicates. The easiest way to remove repeated elements is to add the contents to a Set (which will not allow duplicates) and then add the Set back to the ArrayList:

```Set<String> set = new HashSet<>(yourList);
yourList.clear();