Using Java Using Java - AS Nida

Object Oriented Programming
Using Java
Enumerated Types
Copyright © 2006 Pramote Kuacharoen – All rights reserved.
Enumerated Types
Pramote Kuacharoen
Allows variables to hold a restricted set of values
Not required that enum constants be capital letters; however,
the Sun code convention states that constants are named in
capital letters
Can be declared as a separate class, or as a class member,
however, they must not be declared within a method
enum enum enum
enum enum
Size Size Size { { SMALL, SMALL, SMALL, SMALL, MEDIUM, MEDIUM, LARGE, LARGE, EXTRA_LARGE};
EXTRA_LARGE};
Size Size
Size Size
s s
s s
= =
= =
Size.MEDIUM
Size.MEDIUM
Size.MEDIUM
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Ex: Declaring Enums
enum enum
enum enum
Size Size { { SMALL, SMALL, SMALL, MEDIUM, MEDIUM, LARGE, LARGE, EXTRA_LARGE}
EXTRA_LARGE}
EXTRA_LARGE}
class class
class class
Shirt Shirt
Shirt Shirt Shirt
{
{
{
{
Size Size
Size Size
size size; size
size size; size
}
}
public public public
public public
class class
class class
ShirtTest ShirtTest {
{
public public
public public public
static static
static static
void void
void void
main(String
main(String[]
main(String
main(String
main(String[]
main(String
[] [] [] args args {
{
Shirt Shirt
Shirt Shirt
shirt shirt = = new new Shirt();
Shirt();
shirt.size shirt.size
shirt.size shirt.size
= = Size.MEDIUM
Size.MEDIUM;
Size.MEDIUM
Size.MEDIUM
Size.MEDIUM;
Size.MEDIUM
}
}
}
}
Class
Class
Member
Member
class class
class class
Shirt Shirt Shirt
Shirt Shirt Shirt
{
{
{
{
enum enum
enum enum
Size Size { { SMALL, SMALL, MEDIUM, MEDIUM, LARGE, LARGE, EXTRA_LARGE}
EXTRA_LARGE}
Size Size
Size Size
size size; size
size size; size
}
}
public public
public public
class class class
class class
ShirtTest ShirtTest
ShirtTest {
{
public public
public public
static static
static static
void void
void void
main(String
main(String[]
main(String
main(String
main(String[]
main(String
[] [] args args args args {
{
Shirt Shirt
Shirt Shirt
shirt shirt shirt = = new new Shirt();
Shirt();
shirt.size shirt.size
shirt.size
shirt.size shirt.size
= = Shirt.Size.MEDIUM
Shirt.Size.MEDIUM;
Shirt.Size.MEDIUM
Shirt.Size.MEDIUM
Shirt.Size.MEDIUM;
Shirt.Size.MEDIUM
}
}
}
}
Copyright © 2006 Pramote Kuacharoen – All rights reserved.
Optional Semicolon
class class
class class
Shirt Shirt
Shirt Shirt
{
{
{
{
enum enum
enum enum
Size Size { { SMALL, SMALL, SMALL, MEDIUM, MEDIUM, LARGE, LARGE, LARGE, EXTRA_LARGE}
EXTRA_LARGE};
EXTRA_LARGE}
EXTRA_LARGE}
EXTRA_LARGE};
EXTRA_LARGE}
Size Size
Size Size
size size; size
size size; size
}
}
public public
public public public
class class
class class
ShirtTest ShirtTest
ShirtTest {
{
public public
public public
static static
static static
void void
void void
main(String
main(String[]
main(String
main(String
main(String[]
main(String
[] [] args args {
{
Shirt Shirt
Shirt Shirt Shirt
shirt shirt shirt = = new new new Shirt();
Shirt();
shirt.size shirt.size
shirt.size
shirt.size shirt.size
= = Shirt.Size.MEDIUM
Shirt.Size.MEDIUM;
Shirt.Size.MEDIUM
Shirt.Size.MEDIUM
Shirt.Size.MEDIUM;
Shirt.Size.MEDIUM
}
}
}
}
Copyright © 2006 Pramote Kuacharoen – All rights reserved.
Separate
Separate
class
class
It is optional to put a semicolon at the end of the
enum declaration
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Enum: A Special Kind of Class
Enum can have constructors, methods, and
variables
enum enum
enum enum
Size Size {
{
SMALL(15), SMALL(15),
SMALL(15), SMALL(15),
MEDIUM(18), MEDIUM(18),
MEDIUM(18), MEDIUM(18),
LARGE(20), LARGE(20), LARGE(20),
LARGE(20), LARGE(20),
EXTRA_LARGE(25)
EXTRA_LARGE(25)
EXTRA_LARGE(25)
EXTRA_LARGE(25)
EXTRA_LARGE(25)
private private
private private
int int length; length;
length;
Size(int Size(int
Size(int Size(int
length) length) length) {
{
this.length this.length
this.length this.length
= = length; length;
length;
}
}
public public
public public
int int getLength
getLength() getLength
getLength
getLength() getLength
() () {
{
return return
return return return
length;
length;
length;
length;
}
}
}
}
Copyright © 2006 Pramote Kuacharoen – All rights reserved.
public public
public public
class class
class class
Shirt Shirt
Shirt Shirt
{
{
{
{
private private
private private
Size Size
Size Size
size;
size;
size;
size;
The enum Constructors
public public
public public
static static
static static
void void
void void
main(String
main(String[]
main(String
main(String
main(String[]
main(String
[] [] args args {
{
Shirt Shirt
Shirt Shirt
shirt shirt = = new new Shirt();
Shirt();
shirt.size
shirt.size shirt.size
shirt.size shirt.size
= = = Shirt.Size.MEDIUM
Shirt.Size.MEDIUM;
Shirt.Size.MEDIUM
Shirt.Size.MEDIUM
Shirt.Size.MEDIUM;
Shirt.Size.MEDIUM
System.out.println(shirt.size.getLength
System.out.println(shirt.size.getLength();
System.out.println(shirt.size.getLength
System.out.println(shirt.size.getLength
System.out.println(shirt.size.getLength();
System.out.println(shirt.size.getLength
();
();
}
}
}
}
The enum constructors are invoked automatically,
with the arguments defined after the constant value
The enum constructors can have many arguments
The enum constructors can be overloaded
The enum constructors can be define as anonymous
inner class
Copyright © 2006 Pramote Kuacharoen – All rights reserved.
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Ex: Enum with Anonymous Inner Class
enum enum enum
enum enum
Size Size {
{
SMALL(15), SMALL(15),
SMALL(15), SMALL(15),
MEDIUM(18), MEDIUM(18),
MEDIUM(18), MEDIUM(18),
LARGE(20),
LARGE(20),
LARGE(20),
LARGE(20),
EXTRA_LARGE(25) EXTRA_LARGE(25)
EXTRA_LARGE(25) EXTRA_LARGE(25)
{
{
{
{
public public
public public public
String String
String String
getTag getTag() getTag
getTag getTag() getTag
() () {
{
return return return
return return
"Special "Special
"Special "Special
Tag";
Tag";
Tag";
Tag";
}
}
}
}
private private
private private private
int int length;
length; length;
Size(int Size(int
Size(int Size(int
length) length) {
{
this.length this.length
this.length this.length
= = length;
length;
}
}
public public public
public public public
int int getLength
getLength() getLength
getLength
getLength() getLength
() () () {
{
return return return
return return
length;
length;
length;
length;
}
}
public public
public public
String String String
String String
getTag getTag() getTag
getTag getTag() getTag
() () () {
{
return return return
return return
"Standard "Standard
"Standard "Standard
Tag";
Tag";
Tag";
Tag";
}
}
}
}
Copyright © 2006 Pramote Kuacharoen – All rights reserved.
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