A General Introduction to Programming - Beginning Java Programming: The Object-Oriented Approach - page 9

preventive maintenance
Preventive maintenance aims at increasing software maintainability in order to prevent future
errors. A popular example here was the Y2K problem, where companies massively anticipated date
calculation errors in their software programs at the end of the previous century. Another example
concerns the transition of many countries from their own independent currency toward the Euro.
One important activity to facilitate preventive maintenance is documentation. This means that
the application is extended with various comments that are not executed by the compiler, but that
indicate the meaning of the various data elements, procedures, and operations in order to facilitate
future maintenance.
Among the four types of maintenance, perfective maintenance typically takes the main share of all
maintenance efforts (it can even be more than 50%), followed by adaptive, corrective, and preven-
tive maintenance.
The major causes of maintenance problems are unstructured code, lack of documentation, excessive
user demand for changes, lack of user training and understanding, and high user turnover. Many
organizations have standard procedures for maintenance, which typically start with the formal fil-
ing of a change request specifying the modifications needed to the software. Depending on the sever-
ity of the request and the change management strategy adopted by the organization, these change
requests can be grouped and dealt with at fixed time stamps, or treated immediately.
principles of structured programming
To finish this introductory chapter, this section discusses some of the basic principles of structured
programming.
A first important concept is stepwise refinement. . Programs should be designed using a top-down
strategy where the problem statement is subdivided into smaller, more manageable subproblems.
These subproblems can be further broken down into smaller subproblems until each piece becomes
easy to solve. This strategy should decrease the program development time and its maintenance
cost.
Documentation is another important concept. It provides invaluable clarification for complex pro-
gramming statements, which will again facilitate future maintenance operations. Every program-
ming language offers facilities to include documentation lines that are ignored by the compiler or
interpreter but can be easily read and understood by programmers.
Also of key importance is to assign meaningful names to programming concepts such as variables.
Instead of naming a variable i or j without any explicit interpretation, it is much better to use stu-
dent or course , which immediately indicate their meanings.
By incorporating these principles into your programs, you will improve your own work and at the
same time make it possible for others (or even yourself—it's not always easy to remember what you
meant by varX months later) to update and continue using your software. After all, the goal is to
create something useful that people will want to keep using.
That being said, let's immerse ourselves further into the wonderful world of Java programming and
continue with the next chapter!