feat: Add Swap class to demonstrate Java parameter passing and immutability

WHAT the code does:
- Defines a `Swap` class to illustrate why swapping and string modification don’t persist outside methods in Java.
- In `main()`:
  - Declares integers `a = 10`, `b = 20`.
  - Calls `swap(a, b)` → attempts to swap numbers.
  - Prints `a` and `b` → still `10 20` because Java is **pass-by-value**.
  - Declares string `name = "Swapping numbers"`.
  - Calls `changeName(name)` → attempts to reassign.
  - Prints `name` → still `"Swapping numbers"` because strings are **immutable** and reassignment doesn’t affect the caller.

WHY this matters:
- Demonstrates **pass-by-value** semantics in Java.
- Shows difference between reassigning parameters vs modifying objects.
- Highlights **immutability of String** in Java.

HOW it works:
1. `swap(int num1, int num2)`:
   - Swaps locally inside the method.
   - Original `a` and `b` remain unchanged.
2. `changeName(String naam)`:
   - Reassigns `naam` to a new string.
   - Caller’s reference (`name`) is unaffected.
3. Output:
   - `"10 20"` for numbers.
   - `"Swapping numbers"` for string.

Tips & gotchas:
- To persist swapping, use a wrapper class or return swapped values.
- For mutable objects (e.g., arrays), modifications inside methods *will* persist.
- Strings behave differently because they are immutable objects.
- Demonstrates why Java is sometimes confusingly described as “pass-by-value of the reference”.

Use-cases:
- Educational example for **Java parameter passing rules**.
- Interview discussion starter on **immutability and pass-by-value**.
- Foundation for understanding behavior of mutable vs immutable objects.
- Leads into learning about wrapper classes or data structures for swapping.

Short key: class-swap-pass by value-immutability.

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

Author: Someshdiwan

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

@@ -4,21 +4,21 @@ public static void main(String[] args) {
         int b = 20;
 
         // swap numbers code
-//        int temp = a;
-//        a = b;
-//        b = temp;
+        // int temp = a;
+        // a = b;
+        // b = temp;
 
         swap(a, b);
-
         System.out.println(a + " " + b);
 
-        String name = "Kunal Kushwaha";
+        String name = "Swapping numbers";
         changeName(name);
         System.out.println(name);
     }
 
     static void changeName(String naam) {
-        naam = "Rahul Rana"; // creating a new object
+        naam = "Why name doesn’t change when we called this method inside main method." +
+                "you will get answer in the next code.";
     }
 
     static void swap(int num1, int num2) {