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Exception Handling in the Project
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=> Unexpected and unwanted situation is called as exception.

=> When exception occurs our program will be terminated abnormally.

=> To handle exceptions we have below keywords in java

		try
		catch
		throw
		throws
		finally

Note: Using above keyword we can handle exceptions in console apps and in web applications.


=> When Exception occurs in REST API we have to send a meaningful message to client application in JSON format.

=> To handle exceptions in REST API we have 2 approaches

		1) Class Based Exception Handling

		2) Global Exception Handling


=> Class based exception handling means it will handle exceptions related to that particular class only.

@ExceptionHandler(value = Exception.class)
public ResponseEntity<ExInfo> handleException(Exception e) {

	ExInfo info = new ExInfo();
	info.setExCode("EC0001");
	info.setExMsg(e.getMessage());
	info.setExDate(LocalDateTime.now());

	return new ResponseEntity<ExInfo>(info, HttpStatus.INTERNAL_SERVER_ERROR);
}

=> Global exception handling means it is responsible to handle exceptions occured in any class available in the project.

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public class OrdersNotFoundException extends RuntimeException {

	public OrdersNotFoundException(String msg) {
		super(msg);
	}
}
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@Data
public class ExInfo {
	
	private String exCode;
	private String exMsg;
	private LocalDateTime exDate;

}
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@RestControllerAdvice
@Slf4j
public class AppExHandler {

	@ExceptionHandler(value = OrdersNotFoundException.class)
	public ResponseEntity<ExInfo> handleOrdersEx(OrdersNotFoundException one) {
		
		log.error(one.getMessage());

		ExInfo exinfo = new ExInfo();
		exinfo.setExCode("Ex000");
		exinfo.setExMsg(one.getMessage());
		exinfo.setExDate(LocalDateTime.now());

		return new ResponseEntity<ExInfo>(exinfo, HttpStatus.BAD_REQUEST);
	}

	@ExceptionHandler(value = Exception.class)
	public ResponseEntity<ExInfo> handleEx(Exception e) {

		ExInfo exinfo = new ExInfo();
		exinfo.setExCode("Ex001");
		exinfo.setExMsg(e.getMessage());
		exinfo.setExDate(LocalDateTime.now());

		return new ResponseEntity<ExInfo>(exinfo, HttpStatus.INTERNAL_SERVER_ERROR);
	}

}

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@RestControllerAdvice : To represent global exception handler

@ExceptionHandler : To map our method to particular exception