Catching Exceptions From Multiple Methods Withing the Class

Question

In Java, I have a class with a few methods that throw the same custom exception (the custom exception extends the 'Exception' class):

private void setAColor(float r, float g, float b, float a) throws AnException {}
private void setBColor(float r, float g, float b, float a) throws AnException {}
private void setCColor(float r, float g, float b, float a) throws AnException {}

Instead of having the user handle these exceptions, I would like to be able to catch them and handle them within the class. Each method exception will be caught in the exact same way. I do not want to have to put the exact same try/catch method block in every single method. Is there a way I can catch these exceptions outside of the body of the methods, but inside of the class?

Thank you for your time, even if you cannot help me.

APPENDING MORE INFORMATION:
These methods may be called up until a certain point: After a method is called that sets the variable "isImmutable" to true, these methods should no longer be able to change anything about the object. Hence, if one of these methods are called after "isImmutable" is set to true, then they should throw an exception called "ImmutableException". For /this particular implementation/, I want to be able to handle these myself instead of going to every single point in the code that these methods are called and handling them then exact same way.

What AVD said, or else give more details about what you're trying to do. — Ryan Stewart, Oct 09 '11 at 03:09
I think you can do this with annotations, but I lack the ability to know how — Cory Kendall, Oct 09 '11 at 23:36

Hot Licks · Accepted Answer · 2011-10-09T03:31:43.523

I do not want to have to put the exact same try/catch method block in every single method.

Then don't throw the exception.

Is there a way I can catch these exceptions outside of the body of the methods, but inside of the class?

No.

For /this particular implementation/, I want to be able to handle these myself instead of going to every single point in the code that these methods are called and handling them then exact same way.

That makes no sense. If an error is detected, how do you intend to report it?

After a method is called that sets the variable "isImmutable" to true, these methods should no longer be able to change anything about the object. Hence, if one of these methods are called after "isImmutable" is set to true, then they should throw an exception called "ImmutableException".

Have you considered making your exception a subclass of RuntimeException? Then callers do not need to declare exception handlers -- if no handler the program will be terminated due to "unhandled exception".

Having the ImmutableException implement RuntimeException was exactly what I needed to do. Thank you. — Tanaki, Oct 09 '11 at 03:35

score 1 · Answer 2 · answered Oct 09 '11 at 03:42

1

You could turn the above methods into stub methods which call

setColorDelagator(char abc, ...)

which delegates to

setColorAWithErrorHandling
setColorBWithErrorHandling
setColorCWithErrorHandling

within a try/catch.

I agree this isn't optimal, but I'm unsure of a better way.

answered Oct 09 '11 at 03:42

Cory Kendall

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I just thought of doing this, having COLOR_A, COLOR_B, etc., where you would have to pass one of those in as an argument. But given the way the class is set up, it seems much more intuitive to use the solution that @Daniel proposed. – Tanaki Oct 09 '11 at 03:45

score 0 · Answer 3 · answered Oct 09 '11 at 04:41

To approach it from another angle, have you considered switching to a factory pattern? Rather than have something call to set isImmutable to true, have it call to get an instance where isImmutable is true... and the method in question returns a different version of the class that doesn't have the setters available.

Catching Exceptions From Multiple Methods Withing the Class

3 Answers3