And Now For Something Different

• This Class Exercise was not taken from the Class Notes
• But it demonstrate something important to Java that we have not covered
• Java uses things that look like classes but are called Interfaces
• An interface consists of method headers
• But there is no code for the methods
• When you define a class you can tell the Java interpreter that your class "implements" the interface
• That means your class will define all the methods listed in the interface
• There are advantages to doing this
• Most of these are beyond the scope of this course
• We are using an Interface here because it allows us to do something useful
• If the class we define implements the Interface Comparable
• We can sort objects of this class that are stored in an ArrayList

Unix Setup

• Log in to users3.cs.umb.edu
  You will be in your home directory.
• Go to your it114 directory
  

  cd it114

• Go to your ex directory
  

  cd ex

• Create a directory for this exercise
  

  mkdir  ex36

• Check that the directory was created
  

  ls

Script for this exercise

• Open a text editor
  A program like Sublime.
  Do not use Word or Notepad.
• Paste the text below into the editor window
  

  public class Ex36 {
      public static void main(String[ ]  args)  {
  
      } 
  }

• Save the file as Ex36.java
  
• Change the file so it looks like the code below

• Copy the code below into the file CalendarDate.java

• Compile the source code
  

  javac Ex36.java

• Run the object file
  

  java  Ex36

• You should see
  

  birthdays = [2/22, 10/30, 4/13, 3/16, 4/28]
  birthdays = [2/22, 3/16, 4/13, 4/28, 10/30]

Copy the files to Unix

• Open FileZilla and connect to users3.cs.umb.edu
  You will have to connect using your Unix username and password.
• Copy the file to the to it114/ex/ex36