feat: Add Sum class with overloaded methods for different summations

WHAT the code does:
- Defines a `Sum` class demonstrating different ways of summing integers.
- `sum2()`:
  - Reads two integers from user input via `Scanner`.
  - Returns their sum.
- `sum3(int, int)`:
  - Returns sum of two integers passed as arguments.
- `sum4(int, int, int)`:
  - Returns sum of three integers.
- `main()` demonstrates:
  - Calling `sum2()` interactively.
  - Calling `sum3(20, 30)` → outputs 50.
  - Calling `sum4(100, 200, 300)` → outputs 600.

WHY this matters:
- Demonstrates **method overloading** with different parameter counts.
- Shows difference between interactive input-based and parameter-based methods.
- Reinforces **return values vs printing** in methods.

HOW it works:
1. `sum2()` asks user for two inputs and returns their sum.
2. `sum3()` is a straightforward addition of two integers.
3. `sum4()` adds three integers.
4. All results are stored in variables (`ans`, `ans2`, `ans3`) and printed.

Tips & gotchas:
- `Scanner` in `sum2()` should be closed after use → currently left open.
- Avoid using `System.out.println` after a `return` (unreachable code).
- Method naming (`sum2`, `sum3`, `sum4`) could be improved for clarity.
- Could add `varargs` method (`sum(int... nums)`) to generalize addition.

Use-cases:
- Teaching example for **methods and overloading** in Java.
- Practice with interactive input handling using `Scanner`.
- Useful as a simple calculator demonstration.
- Basis for extending into math utility classes.

Short key: class-sum-method-overloading.

Signed-off-by: https://github.com/Someshdiwan <[email protected]>

Author: Someshdiwan

Section10Methods/Methods 2.O/src/Sum.java

@@ -2,46 +2,36 @@
 
 public class Sum {
     public static void main(String[] args) {
-//        int ans = sum2();
-//        System.out.println(ans);
-
-        int ans = sum3(20, 30);
+        int ans = sum2();
         System.out.println(ans);
+
+        int ans2 = sum3(20, 30);
+        System.out.println(ans2);
+
+        int ans3 = sum4(100, 200, 300);
+        System.out.println(ans3);
     }
 
-    // pass the value of numbers when you are calling the method in main()
+    // pass the value of numbers when you are calling the method in main().
     static int sum3(int a, int b) {
-        int sum = a + b;
-        return sum;
+        return a + b;
     }
 
-    // return the value
     static int sum2() {
         Scanner in = new Scanner(System.in);
+
         System.out.print("Enter number 1: ");
         int num1 = in.nextInt();
+
         System.out.print("Enter number 2: ");
         int num2 = in.nextInt();
+
         int sum = num1 + num2;
         return sum;
-//        System.out.println("This will never execute");
+        // System.out.println("This will never execute");
     }
 
-    static void sum() {
-        Scanner in = new Scanner(System.in);
-        System.out.print("Enter number 1: ");
-        int num1 = in.nextInt();
-        System.out.print("Enter number 2: ");
-        int num2 = in.nextInt();
-        int sum = num1 + num2;
-        System.out.println("The sum = " + sum);
+    static int sum4(int i, int i1, int i2) {
+        return i + i1 + i2;
     }
-
-    /*
-        return_type name (arguments) {
-            // body
-            return statement;
-        }
-
-     */
 }