• Homework Solution
• Number Classes
• Autoboxing & Unboxing
• Enums
• When to use Enums

• Primitive types don't have methods, other than operators, available to them.
• JDK provides corresponding classes to each primitive type
• int -> Integer
• short -> Short
• long -> Long
• float -> Float
• double -> Double
• byte -> Byte

• Auto-boxing is the automagic conversion from a primitive to it's wrapper class.
• Auto-unboxing is the automagic conversion from a wrapper class to it's related primitive.

 Integer x = new Integer(5); //Integer
 int y = 6; //int y = x; //Integer auto-unboxed to int x = 27; //int literal auto-boxed to Integer

• An enum type is a special data type that enables for a variable to be a set of predefined constants. 
  
• The variable must be set to one of the values that have been predefined for it.
• Enums can also have private constructors (called implicitly when being created) and methods and properties.
• Good examples:
• Cardinal Directions (North, South, East, West)
• Days of the Week (Sun, Mon, Tues, etc.)

 public enum Day {
     SUNDAY, 
     MONDAY,
     TUESDAY,
     WEDNESDAY,
     THURSDAY,
     FRIDAY,
     SATURDAY
 }

 Day day1 = Day.MONDAY;
 Day day2 = Day.SATURDAY;

 public enum City {
     SEATTLE("Seattle", 47.6097, 122.3331),
     SAN_FRANCISCO("San Francisco", 37.7833, 122.4167),
     NEW_YORK("New York", 40.7127, 74.0059);

     private String cityName;
     private double latitude;
     private double longitude;

     private City(String cityName, double latitude, double longitude) {
          this.cityName = cityName;
          this.latitude = latitude;
          this.longitude = longitude;
     }

     @Override
     public String toString() {
          return this.cityName;
     }
 }

• Set group of values that don’t change (think of a drop-down box on a web site)
  
• Constants that will be used throughout your program
  
• Good for switches and logic expressions