feat: Demonstrate use of replace and substring with trim on a String

🧪 Functionality:
1. Replace all occurrences of the character `'u'` with `'M'` in the original string.
   ➤ Input: "Abdul Bari Don"
   ➤ Output: "AbdMl Bari Don"

2. Extract a substring from index 3 (inclusive) to 5 (exclusive), and trim any whitespace.
   ➤ Substring: "ul" → After `trim()`: "ul"

🧰 Methods Used:
- `String.replace(char oldChar, char newChar)` — Replaces each occurrence of the specified character.
- `String.substring(int beginIndex, int endIndex)` — Extracts part of the string.
- `String.trim()` — Removes leading and trailing whitespace.

✅ Purpose:
Simple demonstration of basic `String` operations: replacement and substring extraction with trimming.

Signed-off-by: Somesh diwan <[email protected]>

Author: Someshdiwan

Section6StringClassPrinting/src/StringAB2.java

@@ -8,4 +8,4 @@ public static void main(String[] args) {
         String str2 = str.substring(3,5).trim();
         System.out.println(str2);
     }
-}
+}