CollectionUtils


1   /*
2    * Copyright 2006-2007 The Scriptella Project Team.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package scriptella.util;
17  
18  import java.util.Comparator  ;
19  import java.util.Map  ;
20  import java.util.Properties  ;
21  import java.util.TreeMap  ;
22  
23  /**
24   * Collections utility methods.
25   *
26   * @author Fyodor Kupolov
27   * @version 1.0
28   */
29  public final class CollectionUtils {
30      private CollectionUtils() {//Singleton
31      }
32  
33      /**
34       * Comparator similar to {@link String#CASE_INSENSITIVE_ORDER}, but
35       * handles only ASCII characters
36       */
37      private static final Comparator  <String  > ASCII_CASE_INSENSITIVE_ORDER = new Comparator  <String  >() {
38          public int compare(String   s1, String   s2) {
39              int n1=s1.length(), n2=s2.length();
40              int n=n1<n2?n1:n2;
41              for (int i=0; i<n; i++) {
42                  char c1 = s1.charAt(i);
43                  char c2 = s2.charAt(i);
44                  if (c1 != c2) {
45                      if (c1>='A' && c1<='Z') { //Fast lower case
46                          c1=(char)(c1|0x20);
47                      }
48                      if (c2>='A' && c2<='Z') {
49                          c2=(char)(c2|0x20);
50                      }
51                      if (c1 != c2) {
52                          return c1 - c2;
53                      }
54                  }
55              }
56              return n1 - n2;
57          }
58      };
59  
60      /**
61       * Create a map optimized for case insensitive search for keys.
62       * The case insensitive rules are simplified to ASCII chars for performance reasons.
63       *
64       * @return case insensitive map.
65       */
66      public static <V> Map  <String  , V> newCaseInsensitiveAsciiMap() {
67          return new TreeMap  <String  , V>(ASCII_CASE_INSENSITIVE_ORDER);
68      }
69  
70      /**
71       * Returns parameterized version of {@link Properties} the instance
72       * remains the same.
73       * @param properties properties to represent as a map.
74       */
75      @SuppressWarnings  ("unchecked")
76      public static Map  <String  ,String  > asMap(Properties   properties) {
77          return (Map  )properties;
78      }
79  }
80
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags