LabelValue.java

/*******************************************************************************
 *   Gisgraphy Project 
 * 
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 * 
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 *   Lesser General Public License for more details.
 * 
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
 * 
 *  Copyright 2008  Gisgraphy project 
 *  David Masclet <davidmasclet@gisgraphy.com>
 *  
 *  
 *******************************************************************************/
package com.gisgraphy.model;

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><html:options></code> tag.
 * <p>
 * Note: this class has a natural ordering that is inconsistent with equals.
 */
public class LabelValue implements Comparable<LabelValue>, Serializable {

    private static final long serialVersionUID = 3689355407466181430L;

    /**
     * Comparator that can be used for a case insensitive sort of
     * <code>LabelValue</code> objects.
     */
    public static final Comparator<LabelValue> CASE_INSENSITIVE_ORDER = new Comparator<LabelValue>() {
	public int compare(LabelValue o1, LabelValue o2) {
	    String label1 = o1.getLabel();
	    String label2 = o2.getLabel();
	    return label1.compareToIgnoreCase(label2);
	}
    };

    /**
     * Default constructor.
     */
    public LabelValue() {
	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 LabelValue(final String label, final String value) {
	this.label = label;
	this.value = value;
    }

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

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

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

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

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

    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
     * @param o
     *                LabelValue object to compare to
     * @return 0 if labels match for compared objects
     */
    public int compareTo(LabelValue o) {
	// Implicitly tests for the correct type, throwing
	// ClassCastException as required by interface
	String otherLabel = ((LabelValue) o).getLabel();

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

    /**
     * Return a string representation of this object.
     * 
     * @return object as a string
     */
    @Override
    public String toString() {
	StringBuffer sb = new StringBuffer("LabelValue[");
	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 java.lang.Object#equals(java.lang.Object)
     * @param obj
     *                object to compare to
     * @return true/false based on whether values match or not
     */
    @Override
    public boolean equals(Object obj) {
	if (obj == this) {
	    return true;
	}

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

	LabelValue bean = (LabelValue) 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 java.lang.Object#hashCode()
     * @return hashCode
     */
    @Override
    public int hashCode() {
	return (this.getValue() == null) ? 17 : this.getValue().hashCode();
    }
}