Chapter 4
Programming in the Large I
Subroutines
ONE WAY TO BREAK UP A COMPLEX PROGRAM into
manageable pieces is to use subroutines.
A subroutine consists of the instructions for carrying out a certain
task, grouped together and given a name. Elsewhere in the program,
that name can be used as a stand-in for the whole set of instructions.
As a computer executes a program, whenever it encounters
a subroutine name, it executes all the instructions necessary to
carry out the task associated with that subroutine.
Subroutines can be used over and over, at different places in
the program. A subroutine can even be used inside another subroutine.
This allows you to write simple subroutines and then use them to help
write more complex subroutines, which can then be used in turn in other
subroutines. In this way, very complex programs can be built up step-by-step,
where each step in the construction is reasonably simple.
As mentioned in Section 3.7, subroutines in
Java can be either static or non-static. This chapter covers static
subroutines only. Non-static subroutines, which are used in true
object-oriented programming, will be covered in the next chapter.
Contents of Chapter 4:
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