1. More On Enumeration Types
Lecture 10

2. What are enum types? enum types are reference types
an enum type is declared with an enum declaration
an enum declaration is a comma-separated list of enum constants
an enum declaration may include other components of tradational classes such as
constructors
fields
methods
Deitel and Deitel, Java - How to Program,7th Edition, page 288
Show
Craps2.java

3. Restrictions on enum types
enum types are implicitly final, because they declare constants that should not be modified
enum constants are implicitly static
any attempt to create an object of an enum type with operator new results in a compilation error
Deitel and Deitel, Java - How to Program,7th Edition, page 288

4. What can you do with them?
“You can use them anywhere constants can be used such as in the case labels for switch statements and to control enhanced for statements”

5. For Statement Review For statement known as a “counted” loop
use when you know how many times you want to loop
loop control variable can be declared inside loop in which case its scope is the loop and it is not known outside the loop. It is local to the loop.
for (int i = 0; i < 10; i++)
loop control variable can be declared outside loop which which case its scope is the block in which it is declared.
for (i = 0; i < 10; i++)
Show
TestInsideForLoop
TestOutsideForLoop

6. For Statement Review, continued
Java allows you to do “evil” things with a for loop. However, you, the programmer, should not do any of them. Here are the rules to follow:
programmer should not assign values to the loop control variable within the loop
programmer should not alter the value of the terminating value of the loop
Show
TestEvilForLoop

7. Enhanced For Statement
Syntax
For (parameter : arrayName)
statement;
The type of the parameter must be consistent with the type of the elements in the array (i.e. The type specified in the parameter is whatever type of value is stored in the array).
The loop selects one value from the array during each iteration.
The enhanced for statement iterates through successive values in the array, one by one.
Deitel and Deitel, Java - How to Program,7th Edition, page 312
Show
TestEnhancedFor and TestBadEnhancedFor

8. EnumSet
range
public static <E extends Enum<E>> EnumSet<E> range(E from, E to)
Creates an enum set initially containing all of the elements in the range defined by the two specified endpoints. The returned set will contain the endpoints themselves, which may be identical but must not be out of order.
Parameters:
from - the first element in the range
to - the last element in the range
Returns:
an enum set initially containing all of the elements in the range defined by the two specified endpoints
Throws:
NullPointerException - if first or last are null
IllegalArgumentException - if first.compareTo(last) > 0
from API
Show
DeitelBook and DeitelBookDriver