thesis - Faculty of Information and Communication Technologies ...
thesis - Faculty of Information and Communication Technologies ...
thesis - Faculty of Information and Communication Technologies ...
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Chapter 4. Measuring Evolving S<strong>of</strong>tware<br />
the terms Java Interface <strong>and</strong> Java Class where these abstractions are<br />
treated separately in our analysis.<br />
4.5.3 Merge Inner Classes<br />
In Java, the inner class abstraction is provided as a convenience mechanism<br />
to structure the functionality within a class [125]. For example,<br />
inner classes are commonly used to implement event h<strong>and</strong>lers in graphical<br />
user interface applications. More generally, inner classes are used<br />
when an object needs to send another object a block <strong>of</strong> code that can<br />
call the first object’s methods or manipulate its instance variables.<br />
Interestingly, the Java virtual machine specification [180] requires the<br />
compiler to emit a separate class file for each class including the inner<br />
classes defined within a class (<strong>of</strong> Java source code). However, semantically<br />
developers consider inner-classes to be a part <strong>of</strong> the parent class<br />
within the solution design. Especially since instances <strong>of</strong> an inner class<br />
cannot be instantiated without being bound to an enclosing class.<br />
In the Metric Extraction step, inner classes are processed as separate<br />
entities since we use compiled class files as input. However, for the<br />
purposes <strong>of</strong> our study, we treat inner classes as part <strong>of</strong> the parent class<br />
<strong>and</strong> hence merge all metrics collected from inner classes into the parent<br />
class. The key benefit gained by merging is that is allows us to focus<br />
on the core abstractions within the solution rather than the specific<br />
internal representation <strong>of</strong> a class. However, the trade-<strong>of</strong>f is that we<br />
are unable to directly observe the evolution dynamics <strong>of</strong> inner classes<br />
independent <strong>of</strong> their parent classes.<br />
4.5.4 Class Dependency Graph Construction<br />
In order to measure the structural complexity <strong>of</strong> a s<strong>of</strong>tware system we<br />
construct a complete class dependency graph, G T <strong>and</strong> measure certain<br />
properties <strong>of</strong> this graph. When a class uses either data or functionality<br />
from another class, there is a dependency between these classes. In<br />
the context <strong>of</strong> Java s<strong>of</strong>tware, a dependency is created if a class inher-<br />
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