Scope and Access

Introduction: 5.8.0

• variable scope is defined as where the variable is accessible from
  • Determined by where you declare your variable from
    • look at the nearest curly brackets!
  • A variable doesn’t exist outside of it’s scope!

• Class level scope for instance variables
• Method level scope for local variables
  • this includes parameter variables
• block level scope
  • for loop variables and variables defined inside of blocks of code

Local Variables

• Local variables are declared inside a method
• These variables can only be used within the method
  • they do not exist outside!
• Parameter variables are also local variables
• Use local variables for anything used in just one method

Instance variables

• Instance variables are declared at class scope
• these are shared with all methods
  • can be public or private
    • determine accessibility outside of the class
• They have class scope regardless of being public or private

Scope problems

• If a local variable has the same name as an instance variable, the local variable takes prescidense
  • you can use this to refer to the instance variable!

Summary: 5.8.2

• Scope is where a variable is accessible/can be used
• Local variables can only be declared in the body of methods & constructors
  • cannot use modifiers like public or private
  • When a local variable has the same name as an instance variable, the name will refer to the local variable
• formal parameters and variables declared in a method/constructor can only be used in that method/constructor