Abstract:

Many software developers are using the Java language as the 
language of choice on many applications.  This is due to the 
effective use of the object-oriented (OO) paradigm to develop 
large software projects and the ability of the Java language to 
support the increasing use of web technologies in business 
applications. The recent release of the Java version 5.0 has 
further increased its popularity due to the inclusion of new 
features that exist in other OO languages. The transition from 
Java 1.4.x to Java 1.5.x has provided the programmer with more 
flexibility when implementing programs in Java.  

In this paper we present the first study that investigates how 
the characteristics of a class are combined, thereby providing 
feedback on how the features provided by Java 1.4.x or earlier 
and Java 1.5.x or earlier are currently used. The study uses a 
taxonomy of OO classes that provides a mechanism to catalog any 
class written in Java into one of a finite set of groups.  A 
detailed description on how we enumerated all the possible groups 
of Java classes is also provided. Using TaxTOOLJ (a Taxonomy Tool 
for the Object-Oriented Language Java) we cataloged over 155k 
classes from a cross-section of Java applications written in Java 
1.4.x and Java 1.5.x to identify the distribution of groups used 
by developers. We use the data from the study to create prediction 
models that would allow developers to estimate the number of 
different groups of classes, fields and methods that are expected 
to be generated for large Java applications. This knowledge would 
be of significant benefit to aid developers in testing and maintenance 
activities during the software process.