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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/java/lang/Comparable.java | |
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Diffstat (limited to 'libjava/classpath/java/lang/Comparable.java')
-rw-r--r-- | libjava/classpath/java/lang/Comparable.java | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/libjava/classpath/java/lang/Comparable.java b/libjava/classpath/java/lang/Comparable.java new file mode 100644 index 000000000..d4ca63ad8 --- /dev/null +++ b/libjava/classpath/java/lang/Comparable.java @@ -0,0 +1,98 @@ +/* Comparable.java -- Interface for comparaing objects to obtain an ordering + Copyright (C) 1998, 1999, 2001, 2002, 2004, 2005 Free Software Foundation, Inc. + +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; + +/** + * 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 1.5 + */ +public interface Comparable<T> +{ + /** + * 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(T o); +} |