Java Program to Add Two Numbers in 3 Different Ways

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Learn how to add two numbers in Java using three different approaches. We will use a method reference, a normal method, and a lambda expression.

Code Explanation (Step-by-Step)

Using Method Reference

  • First, create a list and store two integer values in it.
  • Convert the list into a stream using the stream() method.
  • The mapToInt() method converts the stream elements into an IntStream .
  • Integer::intValue is a method reference that converts each Integer object to a primitive int.
  • The sum() method calculates the total of all elements in the IntStream.

Using Method Body

  • Create a static method named test() with two integer parameters.
  • Inside the method, add both numbers using the + operator.
  • Return the result to the calling test() method.
  • Call the test() method from the main() method and print the result.

Using Lambda Expression

  • First, create a functional interface named Addable.
  • Declare an add() method that accepts two integer parameters.
  • Implement the add() method using a lambda expression.
  • The lambda expression adds the two numbers and returns the result.
  • Call the add() method through the interface reference and print the output.
				
					import java.util.Arrays;
import java.util.List;

interface Addable {
    int add(int a, int b);
}

public class AdditionMain {

    public static int test(int a, int b) {
        return a + b;
    }

    public static void main(String[] args) {

        // From method reference
        List<Integer> al = Arrays.asList(2, 3);
        int m = al.stream().mapToInt(Integer::intValue).sum();
        System.out.println("Addition from method reference: " + m);

        // From method body
        System.out.println("Addition from method: " + test(1, 2));

        // From lambda expression
        Addable abl = (x, y) -> x + y;
        int result = abl.add(2, 4);
        System.out.println("Sum of (2, 4): " + result);
    }
}

Output :-
Addition from method reference: 5
Addition from method: 3
Sum of (2, 4): 6

How to Add Two Numbers in Java Using Scanner

				
					import java.util.Scanner;

public class AdditionMain {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.println("Enter first number:");
        int num1 = sc.nextInt();

        System.out.println("Enter second number:");
        int num2 = sc.nextInt();

        int sum = num1 + num2;

        System.out.println("Sum of two numbers: " + sum);

        sc.close();
    }
}

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