Accessors

Accessors and variable scope

• variable scope is where the variable is accesible

• parameters and variables declared in method are only avialable in that method.

  • when method ends, the reference of the variable goes away and cannot be accessed again

• instance fields are avialable in any instance method in the class

  • accessors does not affect this

  • stays in scope until the object is deleted (garbage collector)

• static variables are avialable

  • only defined in class not method

  • shared among all instances of any class.

  • not thread safe, must be made final

  • stays in scope until program ends

• loop scope

  • where a variable is declared in the loop ie for loop, and is thus only accessed in the loop.

• block scope

  • variable declared in block, ie if block, can only be used in that block, when block finishes it is destroyed.

• This

  • Example:

    private String username;
    
    public void changeUsername(String newName) {
      this.username = newName;
    }

  • Conflicting local variable and class variable has the same name.

  • this prevents conflicts

  • this refers to the class variable

Public

Package protected (default)

protected

private

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