|
|||||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Object org.apache.commons.lang.enum.Enum org.apache.commons.lang.enum.ValuedEnum
Abstract superclass for type-safe enums with integer values suitable
for use in switch
statements.
NOTE:Due to the way in which Java ClassLoaders work, comparing
Enum
objects should always be done using the equals() method,
not ==
. The equals() method will try ==
first so
in most cases the effect is the same.
To use this class, it must be subclassed. For example:
public final class JavaVersionEnum extends ValuedEnum { //standard enums for version of JVM public static final int JAVA1_0_VALUE = 100; public static final int JAVA1_1_VALUE = 110; public static final int JAVA1_2_VALUE = 120; public static final int JAVA1_3_VALUE = 130; public static final JavaVersionEnum JAVA1_0 = new JavaVersionEnum( "Java 1.0", JAVA1_0_VALUE ); public static final JavaVersionEnum JAVA1_1 = new JavaVersionEnum( "Java 1.1", JAVA1_1_VALUE ); public static final JavaVersionEnum JAVA1_2 = new JavaVersionEnum( "Java 1.2", JAVA1_2_VALUE ); public static final JavaVersionEnum JAVA1_3 = new JavaVersionEnum( "Java 1.3", JAVA1_3_VALUE ); private JavaVersionEnum(String name, int value) { super( name, value ); } public static JavaVersionEnum getEnum(String javaVersion) { return (JavaVersionEnum) getEnum(JavaVersionEnum.class, javaVersion); } public static JavaVersionEnum getEnum(int javaVersion) { return (JavaVersionEnum) getEnum(JavaVersionEnum.class, javaVersion); } public static Map getEnumMap() { return getEnumMap(JavaVersionEnum.class); } public static List getEnumList() { return getEnumList(JavaVersionEnum.class); } public static Iterator iterator() { return iterator(JavaVersionEnum.class); } }
The above class could then be used as follows:
public void doSomething(JavaVersion ver) { switch (ver.getValue()) { case JAVA1_0_VALUE: // ... break; case JAVA1_1_VALUE: // ... break; //... } }
As shown, each enum has a name and a value. These can be accessed using
getName
and getValue
.
The getEnum
and iterator
methods are recommended.
Unfortunately, Java restrictions require these to be coded as shown in each subclass.
An alternative choice is to use the EnumUtils
class.
Field Summary |
Fields inherited from class org.apache.commons.lang.enum.Enum |
iToString |
Constructor Summary | |
protected |
ValuedEnum(String name,
int value)
Constructor for enum item. |
Method Summary | |
int |
compareTo(Object other)
Tests for order. |
protected static Enum |
getEnum(Class enumClass,
int value)
Gets an Enum object by class and value. |
int |
getValue()
Get value of enum item. |
String |
toString()
Human readable description of this Enum item. |
Methods inherited from class org.apache.commons.lang.enum.Enum |
equals, getEnum, getEnumClass, getEnumList, getEnumMap, getName, hashCode, iterator, readResolve |
Methods inherited from class java.lang.Object |
clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Constructor Detail |
protected ValuedEnum(String name, int value)
name
- the name of enum itemvalue
- the value of enum itemMethod Detail |
protected static Enum getEnum(Class enumClass, int value)
Gets an Enum
object by class and value.
This method loops through the list of Enum
,
thus if there are many Enum
s this will be
slow.
enumClass
- the class of the Enum
to getvalue
- the value of the Enum
to get
IllegalArgumentException
- if the enum class is null
public final int getValue()
Get value of enum item.
public int compareTo(Object other)
Tests for order.
The default ordering is numeric by value, but this can be overridden by subclasses.
compareTo
in interface Comparable
compareTo
in class Enum
other
- the other object to compare to
0
of equal
ClassCastException
- if other is not an Enum
NullPointerException
- if other is null
Comparable.compareTo(Object)
public String toString()
Human readable description of this Enum
item.
toString
in class Enum
type[name=value]
, for example:
JavaVersion[Java 1.0=100]
. Note that the package name is
stripped from the type name.
|
|||||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |