feat: demonstrate enum usage with ordinal(), equality checks, and switch-case

WHAT was added:
- Defined an `enum Status { Running, failed, Pending, Success }` to represent task states.
- Showcased:
  - Printing enum constants directly.
  - Using `ordinal()` to get the constant’s position.
  - Comparing enum values with `==` for conditional logic.
  - Using `switch` on enum constants.

WHY this matters:
- Enums provide type-safe constants, making code more readable and less error-prone than using raw integers or strings.
- `ordinal()` shows the position of the enum in its declaration (e.g., `Running → 0`, `Success → 3`).
- Equality (`==`) and `switch-case` improve clarity when checking state transitions.

HOW it works:
1. Print constants:
   - `Status.Running → Running`
   - `Status.Success → Success`
2. Print ordinals:
   - `Status.Running.ordinal() → 0`
   - `Status.Success.ordinal() → 3`
3. Conditional check with `if-else` to print messages depending on status.
4. `switch(s)` statement executes matching case block (e.g., `Running → "All Good"`).

REAL-LIFE APPLICATIONS:
- Workflow states → `PENDING`, `RUNNING`, `FAILED`, `SUCCESS`.
- Order status → `PLACED`, `SHIPPED`, `DELIVERED`, `CANCELLED`.
- Payment lifecycle → `INITIATED`, `PROCESSING`, `SUCCESS`, `FAILED`.
- Job scheduling → `WAITING`, `RUNNING`, `COMPLETED`.

NOTES / BEST PRACTICES:
- Avoid relying on `ordinal()` for persistence since reordering constants changes values.
- Prefer `name()` or custom fields for saving state in databases.
- Enum in `switch` improves readability compared to multiple `if-else` chains.

KEYWORDS:
enum, ordinal, switch-case, workflow states, type-safe constants, real-world enum usage.

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

Author: Someshdiwan

Section20JAVA.lang.Package/src/Enum2.java

@@ -1,11 +1,11 @@
-enum Status
-{
+enum Status {
     Running, failed, Pending, Success;
 }
 
 public class Enum2 {
     public static void main(String[] args) {
         int i =5;
+
         Status s = Status.Running;
         System.out.println(s);
         System.out.println(s.ordinal());
@@ -26,8 +26,7 @@ else if(s2==Status.Pending)
             System.out.println("Done");
 
         Status s3=Status.Success;
-        switch(s)
-        {
+        switch(s) {
             case Running:
                 System.out.println("All Good");
                 break;
@@ -45,4 +44,22 @@ else if(s2==Status.Pending)
                 break;
         }
     }
-}
+}
+
+/*
+1. ordinal():
+   - Enum constant ki position (0-based index) return karta hai.
+   - Example: Running -> 0, failed -> 1, Pending -> 2, Success -> 3.
+
+2. Comparison:
+   - Enums ko == se compare karte hain (safe hai, equals() ki zaroorat nahi).
+   - if(s2 == Status.Pending) ✅
+
+3. switch-case:
+   - Enums directly switch-case me use hote hain.
+   - Cleaner aur faster than multiple if-else.
+
+4. Enum constants:
+   - Always UPPERCASE likhne ka convention hota hai (Running → RUNNING).
+   - Aapke enum me "failed" lowercase hai, technically valid hai but not standard convention.
+*/