TYPES, VALUES, AND VARIABLES

Kinds of Variables

4.5.3

4.

Method parameters

 ( 8.4.1) name argument values passed to a method. For

every parameter declared in a method declaration, a new parameter variable is

created each time that method is invoked ( 15.11). The new variable is initial 

ized with the corresponding argument value from the method invocation. The

method parameter effectively ceases to exist when the execution of the body

of the method is complete.

5.

Constructor parameters

 ( 8.6.1) name argument values passed to a construc 

tor. For every parameter declared in a constructor declaration, a new parame 

ter variable is created each time a class instance creation expression ( 15.8) or

explicit constructor invocation ( 8.6.5) invokes that constructor. The new

variable is initialized with the corresponding argument value from the cre 

ation expression or constructor invocation. The constructor parameter effec 

tively ceases to exist when the execution of the body of the constructor is

complete.

6. An

exception handler parameter

 is created each time an exception is caught

by a

catch

 clause of a

try

 statement ( 14.18). The new variable is initialized

with the actual object associated with the exception ( 11.3,  14.16). The

exception handler parameter effectively ceases to exist when execution of the

block associated with the

catch

 clause is complete.

7.

Local variables

 are declared by local variable declaration statements ( 14.3).

Whenever the flow of control enters a block ( 14.2) or

for

 statement

( 14.12), a new variable is created for each local variable declared in a local

variable declaration statement immediately contained within that block or

for

statement. A local variable declaration statement may contain an expression

which initializes the variable. The local variable with an initializing expres 

sion is not initialized, however, until the local variable declaration statement

that declares it is executed. (The rules of definite assignment ( 16) prevent the

value of a local variable from being used before it has been initialized or oth 

erwise assigned a value.) The local variable effectively ceases to exist when

the execution of the block or

for

 statement is complete.

Were it not for one exceptional situation, a local variable could always be

regarded as being created when its local variable declaration statement is exe 

cuted. The exceptional situation involves the

switch

 statement ( 14.9), where

it is possible for control to enter a block but bypass execution of a local vari 

able declaration statement. Because of the restrictions imposed by the rules of

definite assignment ( 16), however, the local variable declared by such a

bypassed local variable declaration statement cannot be used before it has

been definitely assigned a value by an assignment expression ( 15.25).

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