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 {@link EnumUtils} class.
Gets an Enum object by class and value.
This method loops through the list of Enum,
* thus if there are many Enums this will be
* slow.
Enum to get
* @param value the value of the Enum to get
* @return the enum object, or null if the enum does not exist
* @throws IllegalArgumentException if the enum class is null
*/
protected static Enum getEnum(Class enumClass, int value) {
if (enumClass == null) {
throw new IllegalArgumentException("The Enum Class must not be null");
}
List list = Enum.getEnumList(enumClass);
for (Iterator it = list.iterator(); it.hasNext();) {
ValuedEnum enum = (ValuedEnum) it.next();
if (enum.getValue() == value) {
return enum;
}
}
return null;
}
/**
* Get value of enum item.
* * @return the enum item's value. */ public final int getValue() { return iValue; } /** *Tests for order.
* *The default ordering is numeric by value, but this * can be overridden by subclasses.
* * @see java.lang.Comparable#compareTo(Object) * @param other the other object to compare to * @return -ve if this is less than the other object, +ve if greater than, *0 of equal
* @throws ClassCastException if other is not an Enum
* @throws NullPointerException if other is null
*/
public int compareTo(Object other) {
return iValue - ((ValuedEnum) other).iValue;
}
/**
* Human readable description of this Enum item.
type[name=value], for example:
* JavaVersion[Java 1.0=100]. Note that the package name is
* stripped from the type name.
*/
public String toString() {
if (iToString == null) {
String shortName = ClassUtils.getShortClassName(getEnumClass());
iToString = shortName + "[" + getName() + "=" + getValue() + "]";
}
return iToString;
}
}