Class 19: Interfaces

Held: Tuesday, 27 September 2005

Summary: Today we learn how Java's interfaces allow us to separate the general capabilities of our classes from the particular implementations we choose.

Related Pages:

• EBoard.
• Reading on interfaces.
• Lab on interfaces.

Assignments

• Read Reusing and Generalizing Code, Strategy One: Polymorphism in Java in Espresso.
• Prepare any final questions you have on the exam.

Notes:

• I'm not sure there are enough hours in the day for me to get all the readings and labs written, so I'm once again behind in preparing tomorrow's reading. Expect it in a few hours.
• Are there questions on the exam?

Overview:

• Review of reading.
• Lab.

Interfaces

• Goal: Separate what a class does from how it does it.
• Why? Clarifies; permits multiple implementations; supports polymorphism (coming next)
• Syntax:

  public interface InterfaceName
  {
    // ...
  } // interface InterfaceName
  

• Writing the corresponding class

  public class ClassName
    implements InterfaceName
  {
    // ...
  } // class ClassName
  

Lab

• Do the lab.