feat: Implement Custom Exception Handling with Error Codes and Messages

src/main/java/com/app/controller/HomeController.java

@@ -1,15 +1,29 @@
 package com.app.controller;
 
+import com.app.exception.CustomException;
+import lombok.RequiredArgsConstructor;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 
 @RestController
+@RequiredArgsConstructor
 public class HomeController {
 
+
     @GetMapping
-    public ResponseEntity<String> home(){
+    public ResponseEntity<String> home() {
         return new ResponseEntity<>("Running.....", HttpStatus.OK);
     }
+
+    @GetMapping("exception")
+    public ResponseEntity<String> exceptionTest(@RequestParam(required = false) Integer id) {
+        if (id == null) {
+            throw new CustomException("E0001", "Data Not found", HttpStatus.NOT_FOUND);
+        }
+        return new ResponseEntity<>("Running.....", HttpStatus.OK);
+    }
+
 }

src/main/java/com/app/exception/CustomException.java

@@ -0,0 +1,25 @@
+package com.app.exception;
+
+import lombok.Getter;
+import org.springframework.http.HttpStatus;
+@Getter
+public class CustomException  extends RuntimeException {
+
+    private final String errorCode;      // Custom error code (e.g., "E1001")
+    private final String errorMessage;   // Detailed error message
+    private final HttpStatus httpStatus; // Associated HTTP status code
+
+    /**
+     * Constructor for CustomException.
+     *
+     * @param errorCode    The custom error code.
+     * @param errorMessage The error message.
+     * @param httpStatus   The HTTP status associated with the error.
+     */
+    public CustomException(String errorCode, String errorMessage, HttpStatus httpStatus) {
+        super(errorMessage);  // Pass the message to the superclass (RuntimeException)
+        this.errorCode = errorCode;
+        this.errorMessage = errorMessage;
+        this.httpStatus = httpStatus;
+    }
+}

src/main/java/com/app/exception/GlobalExceptionHandler.java

@@ -0,0 +1,46 @@
+package com.app.exception;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.RestControllerAdvice;
+
+import java.time.LocalDateTime;
+import java.util.HashMap;
+import java.util.Map;
+
+@RestControllerAdvice
+public class GlobalExceptionHandler {
+    /**
+     * Handles custom exceptions with error codes and messages.
+     *
+     * @param ex The CustomException to handle.
+     * @return A ResponseEntity with structured error response.
+     */
+    @ExceptionHandler(CustomException.class)
+    public ResponseEntity<Object> handleCustomException(CustomException ex) {
+        Map<String, Object> response = new HashMap<>();
+        response.put("timestamp", LocalDateTime.now());
+        response.put("status", ex.getHttpStatus().value());
+        response.put("errorCode", ex.getErrorCode());
+        response.put("message", ex.getErrorMessage());
+
+        return new ResponseEntity<>(response, ex.getHttpStatus());
+    }
+
+    /**
+     * Handles all other unexpected exceptions.
+     *
+     * @param ex The generic Exception to handle.
+     * @return A ResponseEntity with error details.
+     */
+    @ExceptionHandler(Exception.class)
+    public ResponseEntity<Object> handleGenericException(Exception ex) {
+        Map<String, Object> response = new HashMap<>();
+        response.put("timestamp", LocalDateTime.now());
+        response.put("status", HttpStatus.INTERNAL_SERVER_ERROR.value());
+        response.put("errorCode", "E5000");
+        response.put("message", "An unexpected error occurred: " + ex.getMessage());
+        return new ResponseEntity<>(response, HttpStatus.INTERNAL_SERVER_ERROR);
+    }
+}