Error codes with variable String descriptions in Java

Question

I would like to have error codes in my Java project, but they should have variable String descriptions. For example, I might have two BadCharacterCount errors, but I'd like to represent them as two different strings, e.g. "Bad character count: expected 50, got 60" and "Bad character count: expected 40, got 70." I'd like to be able to recognize both of these cases as BadCharacterCount errors, and ideally have these in an enum of some sort.

There's a nice discussion of a similar problem here: Best way to define error codes/strings in Java?

However, they don't deal with the case of variable error Strings... Any ideas?

score 0 · Answer 1 · answered Jul 16 '11 at 01:27

0

Consider using the error string as a format for String.format(). Of course, you then have to be careful to have your arguments for each error line up correctly with the particular format.

answered Jul 16 '11 at 01:27

Ed Staub

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score 0 · Accepted Answer · answered Jul 16 '11 at 01:29

I think your two error descriptions:

Bad character count: expected 50, got 60

And:

Bad character count: expected 40, got 70.

Are already the same. The string is:

Bad character count: expected %s, got %s.

Then when you need to construct the error message, just make sure to pass it through String.format:

String.Format(Error.BadCharacterCount, 50, 60)

And

String.Format(Error.BadCharacterCount, 40, 70)

score 0 · Answer 3 · answered Jul 16 '11 at 01:29

You could have something like this:

public class BadCharacterCountException extends Exception {
    public BadCharacterCountException(int expected, int recieved) {
       super("Bad character count: expected " + expected + ", got " + recieved + ".");
    }
}

or

public enum ErrorCode {
    BadCharacterCount("Bad character count: expected {0}, got {1}.");

    private final String message;
    private ErrorCode(String message){
        this.message = message;
    }

    public String getErrorMessage(Object... args) {
        return MessageFormat.format(message, args);
    }
}

Error codes with variable String descriptions in Java

3 Answers3