| The Chapter 4, "Flow Control," started discussing scope and scoping rules, but now you have enough knowledge to formalize these concepts. The scope of an identifier for a variable, reference, or method is the portion of the program in which the identifier can be referenced. There are three types of scope defined in Java: Class Scope: Available to all methods in the class Block Scope: Available only with the block it is declared to, or within nested blocks Method Scope: Special type for labels used with break and continue statements
Listing 5.3 shows a sample application with variables at differing scopes. Listing 5.3 Scope.java public class Scope { static int x = 5; public static int timesX( int n ) { int result = n*x; return result; } public static void main( String[] args ) { int m = 10; System.out.println( "m times x = " + timesX( m ) ); } } In Listing 5.3 there are 3 variables: x, n, and m. Table 5.1 lists the type of scope they have and to which method (if applicable). Table 5.1. Scope.java Variable Scoping| Variable | Scope | Relation |
|---|
| x | Class Scope | The entire Scope class | | n | Local/Block | The timesX method | | m | Local/Block | The main method |
x is a variable defined outside of a method and inside the class Scope, so it is said to have class scope, and is therefore visible from all methods in the class. m is defined inside the main method, so it has local or block scope to the main method. n is declared inside the parameter list of the timesX method, so it has local or block scope to the timesX method. A local variable declared in a block can only be used in that block or nested blocks within that block. | 
