Java Reference
In-Depth Information
Self-Test Exercises
27. What would be the last line in the dialog in Display 4.18 if the user entered the
following input line instead of the one shown in Display 4.18? (The comma is
omitted.)
Savitch Walter None
28. What would be the last line in the dialog in Display 4.18 if the user entered the
following input line instead of the one shown in Display 4.18?
Tom, Dick, and Harry
Chapter Summary
•
Objects have both instance variables and methods. A class is a type whose values
are objects. All objects in a class have the same methods and the same types of
instance variables.
•
There are two main kinds of methods: methods that return a value and
void
methods. (Some specialized methods, such as constructors, are neither
void
meth-
ods nor methods that return a value.)
•
When defining a method, the
this
parameter is a name used for the calling object.
•
Normally, your classes should have both an
equals
method and a
toString
method.
•
If an instance variable or method is marked
private
, then it cannot be directly
referenced anyplace except in the definition of a method of the same class.
•
Outside of the class in which it is defined, a private instance variable can be
accessed via accessor methods and changed via mutator methods.
•
A variable declared in a method is said to be a
local variable
. The meaning of a
local variable is confined to the method in which it is declared. The local variable
goes away when a method invocation ends. The name of a local variable can be
reused for something else outside of the method in which it is declared.
•
A parameter is like a blank in a method definition that is filled in with an argu-
ment when the method is invoked. A parameter is actually a local variable that is
initialized to the value of the corresponding argument. This is known as the
call-
by-value
parameter-passing mechanism.
•
If a variable is used as an argument to a method, then only the value of the vari-
able, not the variable itself, is plugged in to the corresponding parameter.
