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Term |
Description |
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Number of Classes |
The number of concrete and abstract classes (and interfaces)
in the package is an indicator of the extensibility of the
package.
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Afferent Couplings |
The number of other packages that depend upon classes within
the package is an indicator of the package's responsibility.
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Efferent Couplings |
The number of other packages that the classes in the package
depend upon is an indicator of the package's independence.
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Abstractness |
The ratio of the number of abstract classes (and interfaces)
in the analyzed package to the total number of classes in
the analyzed package. The range for this metric is 0 to 1,
with A=0 indicating a completely concrete package and A=1
indicating a completely abstract package.
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Instability |
The ratio of efferent coupling (Ce) to total coupling (Ce /
(Ce + Ca)). This metric is an indicator of the package's
resilience to change. The range for this metric is 0 to 1,
with I=0 indicating a completely stable package and I=1
indicating a completely instable package.
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Distance |
The perpendicular distance of a package from the idealized
line A + I = 1. This metric is an indicator of the package's
balance between abstractness and stability. A package
squarely on the main sequence is optimally balanced with
respect to its abstractness and stability. Ideal packages
are either completely abstract and stable (x=0, y=1) or
completely concrete and instable (x=1, y=0). The range for
this metric is 0 to 1, with D=0 indicating a package that is
coincident with the main sequence and D=1 indicating a
package that is as far from the main sequence as possible.
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Cycles |
Packages participating in a package dependency cycle are in
a deadly embrace with respect to reusability and their
release cycle. Package dependency cycles can be easily
identified by reviewing the textual reports of dependency
cycles. Once these dependency cycles have been identified
with JDepend, they can be broken by employing various
object-oriented techniques.
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