Java tutorial
/* * Copyright 2002-2004 The Apache Software Foundation. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.commons.lang.enums; import java.util.Iterator; import java.util.List; import org.apache.commons.lang.ClassUtils; /** * <p> * Abstract superclass for type-safe enums with integer values suitable for use in <code>switch</code> statements. * </p> * * <p> * <em>NOTE:</em>Due to the way in which Java ClassLoaders work, comparing <code>Enum</code> objects should always be done using * the equals() method, not <code>==</code>. The equals() method will try <code>==</code> first so in most cases the effect is the * same. * </p> * * <p> * To use this class, it must be subclassed. For example: * </p> * * <pre> * 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); * } * } * </pre> * * <p> * The above class could then be used as follows: * </p> * * <pre> * public void doSomething(JavaVersion ver) { * switch (ver.getValue()) { * case JAVA1_0_VALUE: * // ... * break; * case JAVA1_1_VALUE: * // ... * break; * //... * } * } * </pre> * * <p> * As shown, each enum has a name and a value. These can be accessed using <code>getName</code> and <code>getValue</code>. * </p> * * <p> * The <code>getEnum</code> and <code>iterator</code> 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. * </p> * * @deprecated Replaced by {@link org.apache.commons.lang.enums.ValuedEnum * org.apache.commons.lang.enums.ValuedEnum} and will be removed in * version 3.0. All classes in this package * net.sourceforge.fenixedu.net.sourceforge.fenixedu.are deprecated * and repackaged to {@link org.apache.commons.lang.enums} since <code>enum</code> is a Java 1.5 keyword. * @see org.apache.commons.lang.enums.ValuedEnum * @author Apache Avalon project * @author Stephen Colebourne * @since 1.0 * @version $Id$ */ @Deprecated public abstract class ValuedEnum extends Enum { /** Lang version 1.0.1 serial compatibility */ private static final long serialVersionUID = -7129650521543789085L; /** * The value contained in enum. */ private final int iValue; /** * Constructor for enum item. * * @param name * the name of enum item * @param value * the value of enum item */ protected ValuedEnum(String name, int value) { super(name); iValue = value; } /** * <p> * Gets an <code>Enum</code> object by class and value. * </p> * * <p> * This method loops through the list of <code>Enum</code>, thus if there are many <code>Enum</code>s this will be slow. * </p> * * @param enumClass * the class of the <code>Enum</code> to get * @param value * the value of the <code>Enum</code> to get * @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, 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 valuedEnum = (ValuedEnum) it.next(); if (valuedEnum.getValue() == value) { return valuedEnum; } } return null; } /** * <p> * Get value of enum item. * </p> * * @return the enum item's value. */ public final int getValue() { return iValue; } /** * <p> * Tests for order. * </p> * * <p> * The default ordering is numeric by value, 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 <code>Enum</code> * @throws NullPointerException * if other is <code>null</code> */ @Override public int compareTo(Object other) { return iValue - ((ValuedEnum) other).iValue; } /** * <p> * Human readable description of this <code>Enum</code> item. * </p> * * @return String in the form <code>type[name=value]</code>, for example: <code>JavaVersion[Java 1.0=100]</code>. Note that * the package * net.sourceforge.fenixedu.net.sourceforge.fenixedu.name is * stripped from the type name. */ @Override public String toString() { if (iToString == null) { String shortName = ClassUtils.getShortClassName(getEnumClass()); iToString = shortName + "[" + getName() + "=" + getValue() + "]"; } return iToString; } }