Instance Variables (Non-Static Fields)
Ø Technically speaking,
objects store their individual states in "non-static fields", that
is, fields declared without the static keyword.
Ø Non-static fields are also
known as instance variables because their values are unique to
each instance of a class
Class Variables (Static Fields)
Ø A class variable is
any field declared with the static modifier, this tells
the compiler that there is exactly one copy of this variable in existence,
regardless of how many times the class has been instantiated
Local Variables
Ø Similar
to how an object stores its state in fields, a method will often store its
temporary state in local variables.
Ø The
syntax for declaring a local variable is similar to declaring a field (for
example, int c= 0;). There is no special keyword designating a variable as
local; that determination comes entirely from the location in which the
variable is declared — which is between the opening and closing braces of a
method.
Ø As
such, local variables are only visible to the methods in which they are
declared; they are not accessible from the rest of the class.
Parameters
Ø The
signature for the main
method
is public
static void main(String[] args).
Here, the args variable
is the parameter to this method. The important thing to remember is that
parameters are always classified as "variables" not
"fields".
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