feat(WithoutLambdaExpression): add Employee interface with SoftwareEngineer implementation

What
- Added Employee interface in package WithoutLambdaExpression with single method getName().
- Added SoftwareEngineer class implementing Employee:
  - Overrides getName() to return "Software Engineer".
- Added Main class demonstrating usage:
  - Creates Employee reference pointing to new SoftwareEngineer().
  - Prints result of getName().

Why
- Shows traditional approach of implementing functional interfaces without lambdas.
- Provides contrast with lambda-based example in HowUseLambda package.
- Demonstrates how interface references can hold class instances implementing behavior.

How
- Declared Employee interface with getName() signature.
- Implemented getName() in SoftwareEngineer to return fixed string.
- In Main, created new SoftwareEngineer instance assigned to Employee reference.
- Printed output of getName().

Logic
- Inputs: none (hardcoded return value).
- Outputs: "Software Engineer" printed to stdout.
- Flow:
  1. Instantiate SoftwareEngineer via new SoftwareEngineer().
  2. Assign to Employee reference E.
  3. Call E.getName() → "Software Engineer".
  4. Print result.
- Edge cases handled:
  - Implementation ensures non-null string returned.
  - No risk of NullPointerException.
- Complexity / performance: trivial O(1) operations.
- Concurrency / thread-safety:
  - Class is stateless; safe for multi-threaded execution.
- Error handling:
  - No exceptions expected.

Real-life applications
- Common design pattern where interfaces define contracts and concrete classes implement them.
- Useful for decoupling higher-level logic from specific implementations.
- Pre-Java-8 approach before functional programming and lambdas were available.
- Demonstrates polymorphism basics for beginners.

Notes
- SoftwareEngineer.main() is currently unused; can be removed or used for testing.
- Code can be simplified with lambdas (as shown in HowUseLambda), but this example illustrates explicit class implementation.
- Annotating Employee with @FunctionalInterface would clarify its intended role, though not required here.

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

Author: Someshdiwan

Java 8 Crash Course/Lambda Expression/src/WithoutLambdaExpression/Employee.java

@@ -0,0 +1,5 @@
+package WithoutLambdaExpression;
+
+public interface Employee {
+    String getName();
+}