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1
54 package org.logicalcobwebs.cglib.core;
55
56 import java.util.*;
57 import java.lang.reflect.Array  ;
58
59
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 value = (Object )it.next();
70 Object 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 key = it.next();
83 target.put(source.get(key), key);
84 }
85 }
86
87 public static Object [] filter(Object [] a, Predicate p) {
88 List c = new ArrayList(Arrays.asList(a));
89 filter(c, p);
90 return c.toArray((Object [])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 |
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