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https://issues.apache.org/jira/browse/MATH-195?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12884517#action_12884517
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Phil Steitz commented on MATH-195:
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I disagree with the extreme view that all exceptions should be unchecked. That
is simply bad Java programming, in my opinion. I respectfully disagree with
the opinions of Eckel et al that checked exceptions should not exist. I agree
that exceptions should be unchecked if a) they represent programming errors or
b) there is (certainly) no reasonable recovery (basically, I agree with Bloch
and Sun). But checked exceptions still make sense when a reasonable request
has been made by the caller and due to data or execution context the result is
exceptional. A good [math] example is ConvergenceException and its subclasses.
We can argue about the specificity of these classes and whether each is a
suitable abstraction, but the abstraction that ConvergenceException expresses
is a classic use of checked exceptions. I don't think it is a "programming
error" (nor do I think it reveals a [math] bug) to construct a BrentSolver with
a given absolute accuracy and maximum iterations and pass it a function and
initial point that results in a (checked) MaximumIterationsExceeded exception.
This situation may also be recoverable - that is up to the caller. Throwing an
unchecked exception in that case would be incorrect, IMO. As a user of the
class, I *like* having the try - catch with the advertised exception in my code
(what Luc calls self-documentiing) and seeing it in the javadoc. I also *like*
having the compiler remind me if I omit it.
> Inconsistencies in the Exception hierarchy
> ------------------------------------------
>
> Key: MATH-195
> URL: https://issues.apache.org/jira/browse/MATH-195
> Project: Commons Math
> Issue Type: Improvement
> Affects Versions: 1.1, 1.2, 2.0, Nightly Builds
> Reporter: Thomas Chust
> Assignee: Gilles
> Priority: Minor
> Fix For: 2.1
>
> Original Estimate: 0.17h
> Remaining Estimate: 0.17h
>
> I think there are some inconsistencies in the hierarchy of exceptions used by
> the Commons Math library which could easily be fixed:
> - org.apache.commons.math.linear.MatrixIndexException should really be a
> subclass of
> java.lang.IndexOutOfBoundsException.
> - Either org.apache.commons.math.linear.InvalidMatrixException should be
> checked or
> org.apache.commons.math.random.NotPositiveDefiniteMatrixException and
> org.apache.commons.math.geometry.NotARotationMatrixException should be
> unchecked, but in any case the latter two
> should be subclasses of the former. An unchecked InvalidMatrixException
> should probably be a subclass of
> java.lang.ArithmeticException while a checked InvalidMatrixException
> should be a subclass of
> org.apache.commons.math.MathException.
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