Java Reference
In-Depth Information
11
After a lecture on cosmology and the structure of the solar system,
William James was accosted by a little old lady.
“Your theory that the sun is the center of the solar system, and the earth is
a ball which rotates around it has a very convincing ring to it, Mr. James,
but it's wrong. I've got a better theory,” said the little old lady.
“And what is that, madam?” inquired James politely.
“That we live on a crust of earth which is on the back of a giant turtle.”
Not wishing to demolish this absurd little theory by bringing to bear the
masses of scientific evidence he had at his command, James decided
to gently dissuade his opponent by making her see some of the
inadequacies of her position.
“If your theory is correct, madam,” he asked, “what does this turtle stand on?”
“You're a very clever man, Mr. James, and that's a very good question”
replied the little old lady, “but I have an answer to it. And it is this:
the first turtle stands on the back of a second, far larger, turtle, who
stands directly under him.”
“But what does this second turtle stand on?” persisted James patiently.
To this the little old lady crowed triumphantly. “It's no use, Mr. James—
it's turtles all the way down.”
J. R. ROSS,
Constraints on Variables in Syntax
Introduction
A method definition that includes a call to itself is said to be
recursive
. Like most
modern programming languages, Java allows methods to be recursive; if used with a
little care, this can be a useful programming technique. In this chapter, we introduce
the basic techniques needed for defining successful recursive methods. There is nothing
in this chapter that is truly unique to Java. If you are already familiar with recursion,
you can safely skip this chapter. No new Java elements are introduced here.
recursive
method
Prerequisites
Except for the subsections on binary search and searching for a file, this chapter uses
material only from Chapters 1 - 5 . The subsection entitled “Binary Search” also uses
the basic material on one-dimensional arrays from Chapter 6 and the Example entitled
“Finding a File” uses material from the
File
class in Chapter 10 .
