Java Program To Add Two Number

Adding two numbers is often the very first "real" logic a developer writes in Java. While it seems simple, this exercise introduces you to several fundamental concepts: Variables, Data Types, User Input, and Basic Arithmetic. In a real-world application, this logic is the foundation for everything from calculating the total price in a shopping cart to determining a player's score in a mobile game.

Here's a robust Java program to add two numbers entered by the user:

import java.util.Scanner;

public class AddTwoNumbers {
    public static void main(String[] args) {
        // Create a Scanner object to read input from the standard input stream (keyboard)
        Scanner scanner = new Scanner(System.in);

        System.out.println("--- Basic Addition Tool ---");

        // Prompt the user to enter the first number
        System.out.print("Enter the first number: ");
        double num1 = scanner.nextDouble();

        // Prompt the user to enter the second number
        System.out.print("Enter the second number: ");
        double num2 = scanner.nextDouble();

        // Perform the addition logic
        double sum = num1 + num2;

        // Display the result with a clear message
        System.out.println("Calculation Result: " + num1 + " + " + num2 + " = " + sum);

        // Close the Scanner to free up system resources
        scanner.close();
    }
}

How the Code Works

Let's break down exactly what happens when you run this program:

• The Scanner Class: We import java.util.Scanner at the top. This is a built-in Java utility that allows our program to "listen" to what the user types on their keyboard.
• System.in: When we initialize the Scanner with System.in, we are telling Java to read from the standard input stream.
• Variables (num1, num2): These act as containers in your computer's memory. By declaring them as double, we tell Java to set aside enough space for large numbers with decimal points.
• Input Methods: The nextDouble() method pauses the program and waits for the user to type a number and press Enter.
• Resource Management: We use scanner.close() at the end. In Java, it is good practice to close "streams" once you are finished with them to prevent memory leaks.

Real-World Examples

While adding two numbers is a basic console exercise, this logic is applied everywhere in software development:

• E-commerce: Adding the price of a product and the shipping fee to get the total order cost.
• Finance: Adding a monthly interest amount to a bank account balance.
• Gaming: Adding "Experience Points" (XP) to a player's current level progress.