如何在Spring Boot Java应用程序中提高自定义异常的可读性

Question

We have a typical Spring Boot Java application with Services, Rest Controllers and Repositories.

We use custom runtime exceptions in our services and controllers by re-throwing them from catch blocks and then handle them in a spring global exception handler (via @ControllerAdvice ).

Usually, we use throw new SomeCustomException("Message"); construction, but it looks not so good to me as it's hard to see what exceptions are thrown throughout the code.

Thinking of how I could improve readability of the code, I came up with the idea of creating static final instances and then use them like throw new SOME_CUSTOM_EXCEPTION;

In this case, it is clear what exceptions class can throw and it is easy to check whether they are handled in the global exception handler.

I see some drawbacks with those constant exception instances though. First, what if need to pass an external exception into the custom exception, or there are multiple throws of the same class with different messages?

Another idea is to extract exception messages as constants. But again,sometimes we pass no messages.

Are there best practices of indicating what exceptions a class can throw or I am over-thinking and it is just fine to throw new ?

Answer 1

If you wanted to improve readability, perhaps additional custom exceptions with more detailed names would be enough. Additionally you could have a default message constructor, and store other common message strings inside the exception class as static constants:

public class CustomException {
    public static String ERROR_MESSAGE = "some error message";

    public CustomException() {
        super("Default message")
    }

    public CustomException(String message) {
        super(message)
    }
}

throw new CustomException(CustomException.ERROR_MESSAGE);