labelvaluebean.java.svn-base

MVC开源框架

/*
 * $Id$
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.struts.util;

import java.io.Serializable;

import java.util.Comparator;

/**
 * A simple JavaBean to represent label-value pairs. This is most commonly
 * used when constructing user interface elements which have a label to be
 * displayed to the user, and a corresponding value to be returned to the
 * server. One example is the <code>&lt;html:options&gt;</code> tag.
 *
 * <p> Note: this class has a natural ordering that is inconsistent with
 * equals. </p>
 *
 * @version $Rev$ $Date: 2005-05-07 12:11:38 -0400 (Sat, 07 May 2005)
 *          $
 */
public class LabelValueBean implements Comparable, Serializable {
    /**
     * Comparator that can be used for a case insensitive sort of
     * <code>LabelValueBean</code> objects.
     */
    public static final Comparator CASE_INSENSITIVE_ORDER =
        new Comparator() {
            public int compare(Object o1, Object o2) {
                String label1 = ((LabelValueBean) o1).getLabel();
                String label2 = ((LabelValueBean) o2).getLabel();

                return label1.compareToIgnoreCase(label2);
            }
        };

    // ------------------------------------------------------------- Properties

    /**
     * The property which supplies the option label visible to the end user.
     */
    private String label = null;

    /**
     * The property which supplies the value returned to the server.
     */
    private String value = null;

    // ----------------------------------------------------------- Constructors

    /**
     * Default constructor.
     */
    public LabelValueBean() {
        super();
    }

    /**
     * Construct an instance with the supplied property values.
     *
     * @param label The label to be displayed to the user.
     * @param value The value to be returned to the server.
     */
    public LabelValueBean(String label, String value) {
        this.label = label;
        this.value = value;
    }

    public String getLabel() {
        return this.label;
    }

    public void setLabel(String label) {
        this.label = label;
    }

    public String getValue() {
        return this.value;
    }

    public void setValue(String value) {
        this.value = value;
    }

    // --------------------------------------------------------- Public Methods

    /**
     * Compare LabelValueBeans based on the label, because that's the human
     * viewable part of the object.
     *
     * @see Comparable
     */
    public int compareTo(Object o) {
        // Implicitly tests for the correct type, throwing
        // ClassCastException as required by interface
        String otherLabel = ((LabelValueBean) o).getLabel();

        return this.getLabel().compareTo(otherLabel);
    }

    /**
     * Return a string representation of this object.
     */
    public String toString() {
        StringBuffer sb = new StringBuffer("LabelValueBean[");

        sb.append(this.label);
        sb.append(", ");
        sb.append(this.value);
        sb.append("]");

        return (sb.toString());
    }

    /**
     * LabelValueBeans are equal if their values are both null or equal.
     *
     * @see Object#equals(Object)
     */
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }

        if (!(obj instanceof LabelValueBean)) {
            return false;
        }

        LabelValueBean bean = (LabelValueBean) obj;
        int nil = (this.getValue() == null) ? 1 : 0;

        nil += ((bean.getValue() == null) ? 1 : 0);

        if (nil == 2) {
            return true;
        } else if (nil == 1) {
            return false;
        } else {
            return this.getValue().equals(bean.getValue());
        }
    }

    /**
     * The hash code is based on the object's value.
     *
     * @see Object#hashCode()
     */
    public int hashCode() {
        return (this.getValue() == null) ? 17 : this.getValue().hashCode();
    }
}