Methods: A Deeper Look - Java: How to Program Early Objects - page 225

the value ( 10 ) of field x again (lines 43-44) before returning. The next time method use-
Field is called (line 20), the field has its modified value ( 10 ), so the method outputs 10 ,
then 100 . Finally, in method main , the program outputs the value of local variable x again
(line 22) to show that none of the method calls modified main 's local variable x , because
the methods all referred to variables named x in other scopes.

Principle of Least Privilege
In a general sense, “things” should have the capabilities they need to get their job done,
but no more. An example is the scope of a variable. A variable should not be visible when
it's not needed.

Good Programming Practice 6.3
Declare variables as close to where they're first used as possible.

6.12 Method Overloading
Methods of the same name can be declared in the same class, as long as they have different
sets of parameters (determined by the number, types and order of the parameters)—this
is called method overloading . When an overloaded method is called, the compiler selects
the appropriate method by examining the number, types and order of the arguments in
the call. Method overloading is commonly used to create several methods with the same
name that perform the same or similar tasks, but on different types or different numbers of
arguments. For example, Math methods abs , min and max (summarized in Section 6.3) are
overloaded with four versions each:
1. One with two double parameters.
2. One with two float parameters.
3. One with two int parameters.
4. One with two long parameters.
Our next example demonstrates declaring and invoking overloaded methods. We demon-
strate overloaded constructors in Chapter 8.

Declaring Overloaded Methods
Class MethodOverload (Fig. 6.10) includes two overloaded versions of method square —
one that calculates the square of an int (and returns an int ) and one that calculates the
square of a double (and returns a double ). Although these methods have the same name
and similar parameter lists and bodies, think of them simply as different methods. It may
help to think of the method names as “ square of int ” and “ square of double ,” respectively.

1 // Fig. 6.10: MethodOverload.java

2 // Overloaded method declarations.

3
4 public class MethodOverload

5 {

Fig. 6.10 | Overloaded method declarations. (Part 1 of 2.)