Java Reference
In-Depth Information
return
return total ;
}
Polymorphism is a great boon for software maintenance: if a new subclass is added, the code
in the main program does not change. Further, all the code that is specific to, say, polygon
handling, is all in one place: in the source file for the Polygon class. This is a big improve-
ment over older languages, where type fields in a structure or record were used with case or
switch statements scattered all across the software. Java makes software more reliable and
maintainable with the use of polymorphism.
Passing Values
Problem
You need to pass a number like an int into a routine and get back the routine's updated ver-
sion of that value in addition to the routine's return value.
This often comes up in working through strings; the routine may need to return a boolean ,
say, or the number of characters transferred, but also needs to increment an integer array or
string index in the calling class.
It is also useful in constructors, which can't return a value but may need to indicate that they
have “consumed” or processed a certain number of characters from within a string, such as
when the string will be further processed in a subsequent call.
Solution
Use a specialized class such as the MutableInteger class presented here.
Discussion
The Integer class is one of Java's predefined Number subclasses, mentioned in the Introduc-
tion to Chapter 5 . It serves as a wrapper for an int value and also has static methods for
parsing and formatting integers.
It's fine as it is, but you may want something simpler.
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