KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > logicalcobwebs > cglib > core > CollectionUtils


1 /*
2  * The Apache Software License, Version 1.1
3  *
4  * Copyright (c) 2002 The Apache Software Foundation. All rights
5  * reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright
12  * notice, this list of conditions and the following disclaimer.
13  *
14  * 2. Redistributions in binary form must reproduce the above copyright
15  * notice, this list of conditions and the following disclaimer in
16  * the documentation and/or other materials provided with the
17  * distribution.
18  *
19  * 3. The end-user documentation included with the redistribution,
20  * if any, must include the following acknowledgment:
21  * "This product includes software developed by the
22  * Apache Software Foundation (http://www.apache.org/)."
23  * Alternately, this acknowledgment may appear in the software itself,
24  * if and wherever such third-party acknowledgments normally appear.
25  *
26  * 4. The names "Apache" and "Apache Software Foundation" must
27  * not be used to endorse or promote products derived from this
28  * software without prior written permission. For written
29  * permission, please contact apache@apache.org.
30  *
31  * 5. Products derived from this software may not be called "Apache",
32  * nor may "Apache" appear in their name, without prior written
33  * permission of the Apache Software Foundation.
34  *
35  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
36  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
37  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
38  * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
39  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
40  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
41  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
42  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
43  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
44  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
45  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
46  * SUCH DAMAGE.
47  * ====================================================================
48  *
49  * This software consists of voluntary contributions made by many
50  * individuals on behalf of the Apache Software Foundation. For more
51  * information on the Apache Software Foundation, please see
52  * <http://www.apache.org/>.
53  */

54 package org.logicalcobwebs.cglib.core;
55
56 import java.util.*;
57 import java.lang.reflect.Array JavaDoc;
58
59 /**
60  * @author Chris Nokleberg
61  * @version $Id: CollectionUtils.java,v 1.1 2003/12/12 19:28:11 billhorsman Exp $
62  */

63 public class CollectionUtils {
64     private CollectionUtils() { }
65
66     public static Map bucket(Collection c, Transformer t) {
67         Map buckets = new HashMap();
68         for (Iterator it = c.iterator(); it.hasNext();) {
69             Object JavaDoc value = (Object JavaDoc)it.next();
70             Object JavaDoc key = t.transform(value);
71             List bucket = (List)buckets.get(key);
72             if (bucket == null) {
73                 buckets.put(key, bucket = new LinkedList());
74             }
75             bucket.add(value);
76         }
77         return buckets;
78     }
79
80     public static void reverse(Map source, Map target) {
81         for (Iterator it = source.keySet().iterator(); it.hasNext();) {
82             Object JavaDoc key = it.next();
83             target.put(source.get(key), key);
84         }
85     }
86
87     public static Object JavaDoc[] filter(Object JavaDoc[] a, Predicate p) {
88         List c = new ArrayList(Arrays.asList(a));
89         filter(c, p);
90         return c.toArray((Object JavaDoc[])Array.newInstance(a.getClass().getComponentType(), c.size()));
91     }
92
93     public static Collection filter(Collection c, Predicate p) {
94         Iterator it = c.iterator();
95         while (it.hasNext()) {
96             if (!p.evaluate(it.next())) {
97                 it.remove();
98             }
99         }
100         return c;
101     }
102
103     public static List transform(List c, Transformer t) {
104         List result = new ArrayList(c.size());
105         for (Iterator it = c.iterator(); it.hasNext();) {
106             result.add(t.transform(it.next()));
107         }
108         return result;
109     }
110 }
111     
112
Popular Tags