| /* Comparable.java -- Interface for comparaing objects to obtain an ordering |
| Copyright (C) 1998, 1999, 2001, 2002, 2005 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
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| GNU Classpath is free software; you can redistribute it and/or modify |
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| any later version. |
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| General Public License for more details. |
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| 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. |
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| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
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| 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 |
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| |
| |
| package java.lang; |
| |
| /** |
| * Interface for objects that can be ordering among other objects. The |
| * ordering can be <em>total</em>, such that two objects only compare equal |
| * if they are also equal by the equals method, or <em>partial</em> such |
| * that this is not necessarily true. For example, a case-sensitive |
| * dictionary order comparison of Strings is total, but if it is |
| * case-insensitive it is partial, because "abc" and "ABC" compare as |
| * equal even though "abc".equals("ABC") returns false. However, if you use |
| * a partial ordering, it is a good idea to document your class as |
| * "inconsistent with equals", because the behavior of your class in a |
| * SortedMap will be different than in a HashMap. |
| * |
| * <p>Lists, arrays, and sets of objects that implement this interface can |
| * be sorted automatically, without the need for an explicit |
| * {@link java.util.Comparator}. Note that <code>e1.compareTo(null)</code> |
| * should throw an Exception; as should comparison between incompatible |
| * classes. |
| * |
| * @author Geoff Berry |
| * @author Warren Levy (warrenl@cygnus.com) |
| * @see java.util.Comparator |
| * @see java.util.Collections#sort(java.util.List) |
| * @see java.util.Arrays#sort(Object[]) |
| * @see java.util.SortedSet |
| * @see java.util.SortedMap |
| * @see java.util.TreeSet |
| * @see java.util.TreeMap |
| * @since 1.2 |
| * @status updated to 1.4 |
| */ |
| public interface Comparable |
| { |
| /** |
| * Compares this object with another, and returns a numerical result based |
| * on the comparison. If the result is negative, this object sorts less |
| * than the other; if 0, the two are equal, and if positive, this object |
| * sorts greater than the other. To translate this into boolean, simply |
| * perform <code>o1.compareTo(o2) <em><op></em> 0</code>, where op |
| * is one of <, <=, =, !=, >, or >=. |
| * |
| * <p>You must make sure that the comparison is mutual, ie. |
| * <code>sgn(x.compareTo(y)) == -sgn(y.compareTo(x))</code> (where sgn() is |
| * defined as -1, 0, or 1 based on the sign). This includes throwing an |
| * exception in either direction if the two are not comparable; hence, |
| * <code>compareTo(null)</code> should always throw an Exception. |
| * |
| * <p>You should also ensure transitivity, in two forms: |
| * <code>x.compareTo(y) > 0 && y.compareTo(z) > 0</code> implies |
| * <code>x.compareTo(z) > 0</code>; and <code>x.compareTo(y) == 0</code> |
| * implies <code>x.compareTo(z) == y.compareTo(z)</code>. |
| * |
| * @param o the object to be compared |
| * @return an integer describing the comparison |
| * @throws NullPointerException if o is null |
| * @throws ClassCastException if o cannot be compared |
| */ |
| int compareTo(Object o); |
| } |