Variable Declarations, Typing, and
Initialization
Python |
Java |
Form: <variable>
= <expression> Examples: x = 1 x = x + 3.14 A variable is introduced
and set to an initial value by means of an assignment statement. Any variable can name
any object and can be reset to any object. A variable picks up the
type of the object to which it is currently bound. Type checking and
checking for references to uninitialized variables are done at run time. |
Forms: <type>
<variable>, É, <variable>; <type>
<variable> = <expression>; Examples: int x, y; x = 1; y = 2; int z = 3; A variable has a type,
which is specified when the variable is declared. A variable can only be assigned a value that is compatible
with its type. Type incompatibilities
are caught at compile time. All instance and class
variables are given default values when they are declared. However, the compiler requires the
programmer to assign temporary variables within methods a value before they
can be referenced. Thus, all
variables are guaranteed to have a value at run time. |