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Diffstat (limited to 'libjava/classpath/java/lang/Enum.java')
-rw-r--r-- | libjava/classpath/java/lang/Enum.java | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/libjava/classpath/java/lang/Enum.java b/libjava/classpath/java/lang/Enum.java new file mode 100644 index 00000000000..5344d5c7201 --- /dev/null +++ b/libjava/classpath/java/lang/Enum.java @@ -0,0 +1,248 @@ +/* Enum.java - Base class for all enums + Copyright (C) 2004, 2005 Free Software Foundation + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + +package java.lang; + +import java.io.Serializable; +import java.lang.reflect.Field; + +/** + * This class represents a Java enumeration. All enumerations are + * subclasses of this class. + * + * @author Tom Tromey (tromey@redhat.com) + * @author Andrew John Hughes (gnu_andrew@member.fsf.org) + * @since 1.5 + */ +/* FIXME[GENERICS]: Should be Enum<T extends Enum<T>> + and Comparable<T> */ +public abstract class Enum + implements Comparable, Serializable +{ + + /** + * For compatability with Sun's JDK + */ + private static final long serialVersionUID = -4300926546619394005L; + + /** + * The name of this enum constant. + */ + String name; + + /** + * The number of this enum constant. Each constant is given a number + * which matches the order in which it was declared, starting with zero. + */ + int ordinal; + + /** + * This constructor is used by the compiler to create enumeration constants. + * + * @param name the name of the enumeration constant. + * @param ordinal the number of the enumeration constant, based on the + * declaration order of the constants and starting from zero. + */ + protected Enum(String name, int ordinal) + { + this.name = name; + this.ordinal = ordinal; + } + + /** + * Returns an Enum for a enum class given a description string of + * the enum constant. + * + * @exception NullPointerException when etype or s are null. + * @exception IllegalArgumentException when there is no value s in + * the enum etype. + */ + /* FIXME[GENERICS]: Should be <S extends Enum<S>> S valueOf(Class<S>) */ + public static Enum valueOf(Class etype, String s) + { + if (etype == null || s == null) + throw new NullPointerException(); + + try + { + Field f = etype.getDeclaredField(s); + if (! f.isEnumConstant()) + throw new IllegalArgumentException(s); + /* FIXME[GENERICS]: Should cast to S */ + return (Enum) f.get(null); + } + catch (NoSuchFieldException exception) + { + throw new IllegalArgumentException(s); + } + catch (IllegalAccessException exception) + { + throw new Error("Unable to access Enum class"); + } + } + + /** + * Returns true if this enumeration is equivalent to the supplied object, + * <code>o</code>. Only one instance of an enumeration constant exists, + * so the comparison is simply done using <code>==</code>. + * + * @param o the object to compare to this. + * @return true if <code>this == o</code>. + */ + public final boolean equals(Object o) + { + // Enum constants are singular, so we need only compare `=='. + return this == o; + } + + /** + * Returns the hash code of this constant. This is simply the ordinal. + * + * @return the hash code of this enumeration constant. + */ + public final int hashCode() + { + return ordinal; + } + + /** + * Returns a textual representation of this enumeration constant. + * By default, this is simply the declared name of the constant, but + * specific enumeration types may provide an implementation more suited + * to the data being stored. + * + * @return a textual representation of this constant. + */ + public String toString() + { + return name; + } + + /** + * Returns an integer which represents the relative ordering of this + * enumeration constant. Enumeration constants are ordered by their + * ordinals, which represents their declaration order. So, comparing + * two identical constants yields zero, while one declared prior to + * this returns a positive integer and one declared after yields a + * negative integer. + * + * @param e the enumeration constant to compare. + * @return a negative integer if <code>e.ordinal < this.ordinal</code>, + * zero if <code>e.ordinal == this.ordinal</code> and a positive + * integer if <code>e.ordinal > this.ordinal</code>. + * @throws ClassCastException if <code>e</code> is not an enumeration + * constant of the same class. + */ + public final int compareTo(Enum e) + { + if (getDeclaringClass() != e.getDeclaringClass()) + throw new ClassCastException(); + return ordinal - e.ordinal; + } + + /** + * Returns an integer which represents the relative ordering of this + * enumeration constant. Enumeration constants are ordered by their + * ordinals, which represents their declaration order. So, comparing + * two identical constants yields zero, while one declared prior to + * this returns a positive integer and one declared after yields a + * negative integer. + * + * @param o the enumeration constant to compare. + * @return a negative integer if <code>e.ordinal < this.ordinal</code>, + * zero if <code>e.ordinal == this.ordinal</code> and a positive + * integer if <code>e.ordinal > this.ordinal</code>. + * @throws ClassCastException if <code>e</code> is not an enumeration + * constant of the same class. + */ + /* FIXME[GENERICS]: Remove this method */ + public final int compareTo(Object o) + { + return compareTo((Enum)o); + } + + /** + * Cloning of enumeration constants is prevented, to maintain their + * singleton status. + * + * @return the cloned object. + * @throws CloneNotSupportedException as enumeration constants can't be + * cloned. + */ + protected final Object clone() throws CloneNotSupportedException + { + throw new CloneNotSupportedException("can't clone an enum constant"); + } + + /** + * Returns the name of this enumeration constant. + * + * @return the name of the constant. + */ + public final String name() + { + return name; + } + + /** + * Returns the number of this enumeration constant, which represents + * the order in which it was originally declared, starting from zero. + * + * @return the number of this constant. + */ + public final int ordinal() + { + return ordinal; + } + + /** + * Returns the type of this enumeration constant. This is the class + * corresponding to the declaration of the enumeration. + * + * @return the type of this enumeration constant. + */ + /* FIXME[GENERICS]: Should return Class<T> */ + public final Class getDeclaringClass() + { + Class k = getClass(); + // We might be in an anonymous subclass of the enum class, so go + // up one more level. + if (k.getSuperclass() != Enum.class) + k = k.getSuperclass(); + return k; + } +} |