enum.java

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        iName = name;
        iHashCode = 7 + getEnumClass().hashCode() + 3 * name.hashCode();
        // cannot create toString here as subclasses may want to include other data
    }

    /**
     * Initializes the enumeration.
     * 
     * @param name  the enum name
     * @throws IllegalArgumentException if the name is null or empty or duplicate
     * @throws IllegalArgumentException if the enumClass is null or invalid
     */
    private void init(String name) {
        if (StringUtils.isEmpty(name)) {
            throw new IllegalArgumentException("The Enum name must not be empty or null");
        }
        
        Class enumClass = getEnumClass();
        if (enumClass == null) {
            throw new IllegalArgumentException("getEnumClass() must not be null");
        }
        Class cls = getClass();
        boolean ok = false;
        while (cls != null && cls != Enum.class && cls != ValuedEnum.class) {
            if (cls == enumClass) {
                ok = true;
                break;
            }
            cls = cls.getSuperclass();
        }
        if (ok == false) {
            throw new IllegalArgumentException("getEnumClass() must return a superclass of this class");
        }
        
        // create entry
        Entry entry = (Entry) cEnumClasses.get(enumClass);
        if (entry == null) {
            entry = createEntry(enumClass);
            cEnumClasses.put(enumClass, entry);
        }
        if (entry.map.containsKey(name)) {
            throw new IllegalArgumentException("The Enum name must be unique, '" + name + "' has already been added");
        }
        entry.map.put(name, this);
        entry.list.add(this);
    }

    /**
     * <p>Handle the deserialization of the class to ensure that multiple
     * copies are not wastefully created, or illegal enum types created.</p>
     *
     * @return the resolved object
     */
    protected Object readResolve() {
        Entry entry = (Entry) cEnumClasses.get(getEnumClass());
        if (entry == null) {
            return null;
        }
        return (Enum) entry.map.get(getName());
    }
    
    //--------------------------------------------------------------------------------

    /**
     * <p>Gets an <code>Enum</code> object by class and name.</p>
     * 
     * @param enumClass  the class of the Enum to get, must not
     *  be <code>null</code>
     * @param name  the name of the <code>Enum</code> to get,
     *  may be <code>null</code>
     * @return the enum object, or null if the enum does not exist
     * @throws IllegalArgumentException if the enum class
     *  is <code>null</code>
     */
    protected static Enum getEnum(Class enumClass, String name) {
        Entry entry = getEntry(enumClass);
        if (entry == null) {
            return null;
        }
        return (Enum) entry.map.get(name);
    }

    /**
     * <p>Gets the <code>Map</code> of <code>Enum</code> objects by
     * name using the <code>Enum</code> class.</p>
     *
     * <p>If the requested class has no enum objects an empty
     * <code>Map</code> is returned.</p>
     * 
     * @param enumClass  the class of the <code>Enum</code> to get,
     *  must not be <code>null</code>
     * @return the enum object Map
     * @throws IllegalArgumentException if the enum class is <code>null</code>
     * @throws IllegalArgumentException if the enum class is not a subclass of Enum
     */
    protected static Map getEnumMap(Class enumClass) {
        Entry entry = getEntry(enumClass);
        if (entry == null) {
            return EMPTY_MAP;
        }
        return entry.unmodifiableMap;
    }

    /**
     * <p>Gets the <code>List</code> of <code>Enum</code> objects using the
     * <code>Enum</code> class.</p>
     *
     * <p>The list is in the order that the objects were created (source code order).
     * If the requested class has no enum objects an empty <code>List</code> is
     * returned.</p>
     * 
     * @param enumClass  the class of the <code>Enum</code> to get,
     *  must not be <code>null</code>
     * @return the enum object Map
     * @throws IllegalArgumentException if the enum class is <code>null</code>
     * @throws IllegalArgumentException if the enum class is not a subclass of Enum
     */
    protected static List getEnumList(Class enumClass) {
        Entry entry = getEntry(enumClass);
        if (entry == null) {
            return Collections.EMPTY_LIST;
        }
        return entry.unmodifiableList;
    }

    /**
     * <p>Gets an <code>Iterator</code> over the <code>Enum</code> objects in
     * an <code>Enum</code> class.</p>
     *
     * <p>The <code>Iterator</code> is in the order that the objects were
     * created (source code order). If the requested class has no enum
     * objects an empty <code>Iterator</code> is returned.</p>
     * 
     * @param enumClass  the class of the <code>Enum</code> to get,
     *  must not be <code>null</code>
     * @return an iterator of the Enum objects
     * @throws IllegalArgumentException if the enum class is <code>null</code>
     * @throws IllegalArgumentException if the enum class is not a subclass of Enum
     */
    protected static Iterator iterator(Class enumClass) {
        return Enum.getEnumList(enumClass).iterator();
    }

    //-----------------------------------------------------------------------
    /**
     * <p>Gets an <code>Entry</code> from the map of Enums.</p>
     * 
     * @param enumClass  the class of the <code>Enum</code> to get
     * @return the enum entry
     */
    private static Entry getEntry(Class enumClass) {
        if (enumClass == null) {
            throw new IllegalArgumentException("The Enum Class must not be null");
        }
        if (Enum.class.isAssignableFrom(enumClass) == false) {
            throw new IllegalArgumentException("The Class must be a subclass of Enum");
        }
        Entry entry = (Entry) cEnumClasses.get(enumClass);
        return entry;
    }
    
    /**
     * <p>Creates an <code>Entry</code> for storing the Enums.</p>
     *
     * <p>This accounts for subclassed Enums.</p>
     * 
     * @param enumClass  the class of the <code>Enum</code> to get
     * @return the enum entry
     */
    private static Entry createEntry(Class enumClass) {
        Entry entry = new Entry();
        Class cls = enumClass.getSuperclass();
        while (cls != null && cls != Enum.class && cls != ValuedEnum.class) {
            Entry loopEntry = (Entry) cEnumClasses.get(cls);
            if (loopEntry != null) {
                entry.list.addAll(loopEntry.list);
                entry.map.putAll(loopEntry.map);
                break;  // stop here, as this will already have had superclasses added
            }
            cls = cls.getSuperclass();
        }
        return entry;
    }
    
    //-----------------------------------------------------------------------
    /**
     * <p>Retrieve the name of this Enum item, set in the constructor.</p>
     * 
     * @return the <code>String</code> name of this Enum item
     */
    public final String getName() {
        return iName;
    }

    /**
     * <p>Retrieves the Class of this Enum item, set in the constructor.</p>
     * 
     * <p>This is normally the same as <code>getClass()</code>, but for
     * advanced Enums may be different. If overridden, it must return a
     * constant value.</p>
     * 
     * @return the <code>Class</code> of the enum
     * @since 2.0
     */
    public Class getEnumClass() {
        return getClass();
    }

    /**
     * <p>Tests for equality.</p>
     *
     * <p>Two Enum objects are considered equal
     * if they have the same class names and the same names.
     * Identity is tested for first, so this method usually runs fast.</p>
     *
     * @param other  the other object to compare for equality
     * @return <code>true</code> if the Enums are equal
     */
    public final boolean equals(Object other) {
        if (other == this) {
            return true;
        } else if (other == null) {
            return false;
        } else if (other.getClass() == this.getClass()) {
            // shouldn't happen, but...
            return iName.equals(((Enum) other).iName);
        } else if (((Enum) other).getEnumClass().getName().equals(getEnumClass().getName())) {
            // different classloaders
            try {
                // try to avoid reflection
                return iName.equals(((Enum) other).iName);

            } catch (ClassCastException ex) {
                // use reflection
                try {
                    Method mth = other.getClass().getMethod("getName", null);
                    String name = (String) mth.invoke(other, null);
                    return iName.equals(name);
                } catch (NoSuchMethodException ex2) {
                    // ignore - should never happen
                } catch (IllegalAccessException ex2) {
                    // ignore - should never happen
                } catch (InvocationTargetException ex2) {
                    // ignore - should never happen
                }
                return false;
            }
        } else {
            return false;
        }
    }

    /**
     * <p>Returns a suitable hashCode for the enumeration.</p>
     *
     * @return a hashcode based on the name
     */
    public final int hashCode() {
        return iHashCode;
    }

    /**
     * <p>Tests for order.</p>
     *
     * <p>The default ordering is alphabetic by name, but this
     * can be overridden by subclasses.</p>
     * 
     * @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, <code>0</code> of equal
     * @throws ClassCastException if other is not an Enum
     * @throws NullPointerException if other is <code>null</code>
     */
    public int compareTo(Object other) {
        if (other == this) {
            return 0;
        }
        return iName.compareTo(((Enum) other).iName);
    }

    /**
     * <p>Human readable description of this Enum item.</p>
     * 
     * @return String in the form <code>type[name]</code>, for example:
     * <code>Color[Red]</code>. 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() + "]";
        }
        return iToString;
    }
    
}