Java program to calculate sum of squares of odd and even numbers using lambda expression

Last update on May 09 2025 12:54:53 (UTC/GMT +8 hours)

15. Sum squares of odd/even numbers using lambda

Write a Java program to implement a lambda expression to calculate the sum of squares of all odd and even numbers in a list.

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 integers
    List < Integer > nums = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
    System.out.println("Original list elements: " + nums);
    // Calculate the sum of squares of odd numbers using lambda expression
    int sum_squares_odd = nums.stream()
      .filter(n -> n % 2 != 0)
      .mapToInt(n -> n * n)
      .sum();

    // Calculate the sum of squares of even numbers using lambda expression
    int sum_squares_even = nums.stream()
      .filter(n -> n % 2 == 0)
      .mapToInt(n -> n * n)
      .sum();

    // Print the results
    System.out.println("\nSum of squares of odd numbers: " + sum_squares_odd);
    System.out.println("\nSum of squares of even numbers: " + sum_squares_even);
  }
}

Sample Output:

Original list elements: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Sum of squares of odd numbers: 165

Sum of squares of even numbers: 220

Explanation:

The necessary classes are imported: Arrays and Lists.

In the main method, we create a list of integers called nums using Arrays.asList().

A lambda expression is used to calculate the sum of squares of odd numbers:

Use the stream() method to create a stream of integers from the nums list.
Use the filter() method to filter out odd numbers by checking if the remainder of dividing the number by 2 is not equal to 0.
Use the mapToInt() method to square each odd number.
Use the sum() method to calculate the sum of squares of odd numbers.
Store the result in the variable sum_squares_odd.

A similar lambda expression is used to calculate the sum of squares of even numbers:

Use the filter() method to filter out even numbers by checking if the remainder of dividing the number by 2 is equal to 0.
Store the result in the variable sum_squares_even.

Finally, System.out.println() function prints the result.

Flowchart:

Flowchart: Java Exercises: Java program to calculate sum of squares of odd and even numbers using lambda expression.

For more Practice: Solve these Related Problems:

Write a Java program to implement a lambda expression that calculates the sum of squares of even numbers in a list.
Write a Java program to create a lambda that computes the sum of squares for odd numbers and even numbers separately.
Write a Java program to implement a lambda that filters odd numbers, maps them to their squares, and then sums the result.
Write a Java program to chain lambda expressions that calculate and compare the sum of squares of odd versus even numbers.

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