Using Set and Get Methods

• Private instance variables can be manipulated only by the class's methods.
• Classes typically provide public methods to get and set private instance variables.
• What is gained by this indirect route to getting and setting variables?

  The designer of the class retains control of the class's implementation:

  • public get methods may get "virtual" instance variables.

    For example, in the Time class, there might be a getHours method, even though there may not be a hours instance variable.

  • public set methods may reformat and validate attempts to set instance variables.
• Ultimately, it's the class designer's responsibility to provide data validity checking.

  Java just provides a convenient framework for writing robust code.