View Javadoc

1   /*
2    * $Id: LabelValueBean.java 471754 2006-11-06 14:55:09Z husted $
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *  http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  package org.apache.struts.util;
22  
23  import java.io.Serializable;
24  
25  import java.util.Comparator;
26  
27  /**
28   * A simple JavaBean to represent label-value pairs. This is most commonly
29   * used when constructing user interface elements which have a label to be
30   * displayed to the user, and a corresponding value to be returned to the
31   * server. One example is the <code>&lt;html:options&gt;</code> tag.
32   *
33   * <p> Note: this class has a natural ordering that is inconsistent with
34   * equals. </p>
35   *
36   * @version $Rev: 471754 $ $Date: 2005-05-07 12:11:38 -0400 (Sat, 07 May 2005)
37   *          $
38   */
39  public class LabelValueBean implements Comparable, Serializable {
40      /**
41       * Comparator that can be used for a case insensitive sort of
42       * <code>LabelValueBean</code> objects.
43       */
44      public static final Comparator CASE_INSENSITIVE_ORDER =
45          new Comparator() {
46              public int compare(Object o1, Object o2) {
47                  String label1 = ((LabelValueBean) o1).getLabel();
48                  String label2 = ((LabelValueBean) o2).getLabel();
49  
50                  return label1.compareToIgnoreCase(label2);
51              }
52          };
53  
54      // ------------------------------------------------------------- Properties
55  
56      /**
57       * The property which supplies the option label visible to the end user.
58       */
59      private String label = null;
60  
61      /**
62       * The property which supplies the value returned to the server.
63       */
64      private String value = null;
65  
66      // ----------------------------------------------------------- Constructors
67  
68      /**
69       * Default constructor.
70       */
71      public LabelValueBean() {
72          super();
73      }
74  
75      /**
76       * Construct an instance with the supplied property values.
77       *
78       * @param label The label to be displayed to the user.
79       * @param value The value to be returned to the server.
80       */
81      public LabelValueBean(String label, String value) {
82          this.label = label;
83          this.value = value;
84      }
85  
86      public String getLabel() {
87          return this.label;
88      }
89  
90      public void setLabel(String label) {
91          this.label = label;
92      }
93  
94      public String getValue() {
95          return this.value;
96      }
97  
98      public void setValue(String value) {
99          this.value = value;
100     }
101 
102     // --------------------------------------------------------- Public Methods
103 
104     /**
105      * Compare LabelValueBeans based on the label, because that's the human
106      * viewable part of the object.
107      *
108      * @see Comparable
109      */
110     public int compareTo(Object o) {
111         // Implicitly tests for the correct type, throwing
112         // ClassCastException as required by interface
113         String otherLabel = ((LabelValueBean) o).getLabel();
114 
115         return this.getLabel().compareTo(otherLabel);
116     }
117 
118     /**
119      * Return a string representation of this object.
120      */
121     public String toString() {
122         StringBuffer sb = new StringBuffer("LabelValueBean[");
123 
124         sb.append(this.label);
125         sb.append(", ");
126         sb.append(this.value);
127         sb.append("]");
128 
129         return (sb.toString());
130     }
131 
132     /**
133      * LabelValueBeans are equal if their values are both null or equal.
134      *
135      * @see Object#equals(Object)
136      */
137     public boolean equals(Object obj) {
138         if (obj == this) {
139             return true;
140         }
141 
142         if (!(obj instanceof LabelValueBean)) {
143             return false;
144         }
145 
146         LabelValueBean bean = (LabelValueBean) obj;
147         int nil = (this.getValue() == null) ? 1 : 0;
148 
149         nil += ((bean.getValue() == null) ? 1 : 0);
150 
151         if (nil == 2) {
152             return true;
153         } else if (nil == 1) {
154             return false;
155         } else {
156             return this.getValue().equals(bean.getValue());
157         }
158     }
159 
160     /**
161      * The hash code is based on the object's value.
162      *
163      * @see Object#hashCode()
164      */
165     public int hashCode() {
166         return (this.getValue() == null) ? 17 : this.getValue().hashCode();
167     }
168 }