Scope Rules

• The scope of an identifier is the portion of the program in which the identifier can be referenced.
• There are 2 kinds of scope:
  • class scope:
    • begins with the opening brace, {, of the class definition;
    • ends with the closing brace, }, of the class definition.
    • class scope enables a class's methods to:
      • directly invoke all of the class's methods;
      • directly access all instance variables defined in the class
  • block scope:
    • begins with the identifier's declaration;
    • ends with the closing brace, }, of the block.
    • local variables declared at the beginning of a method have block scope, as do method parameters.
• If a local variable in a method has the same name as an instance variable, then the instance variable is hidden until the block terminates (illustrated with an applet).