NumberConverter.java

/*******************************************************************************
 * Copyright 2006 - 2012 Vienna University of Technology,
 * Department of Software Technology and Interactive Systems, IFS
 * 
 * Licensed 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 eu.scape_project.planning.converters;

import java.io.Serializable;

import javax.faces.application.FacesMessage;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.ConverterException;

/**
 * Converter responsible for transforming between input number as double and its
 * string representation.
 * 
 * @author Hannes Kulovits, Markus Hamm
 */
public class NumberConverter implements Converter, Serializable {

    private static final long serialVersionUID = -6674250183273455339L;

    /**
     * Method responsible for converting the given input string to the wanted
     * double number.
     * 
     * @param context
     *            FacesContext for the request being processed
     * @param component
     *            UIComponent with which this model object value is associated
     * @param value
     *            Input string to be converted.
     * @throws ConverterException
     *             if the input cannot be converted to double.
     * @return Input converted to double value.
     * 
     */
    @Override
    public Object getAsObject(FacesContext context, UIComponent component, String value) {
        // no value provided
        if (value == null || value.trim().length() == 0) {
            FacesMessage message = new FacesMessage();
            message.setSummary("Please enter a value");
            message.setDetail("No value provided");
            message.setSeverity(FacesMessage.SEVERITY_ERROR);
            throw new ConverterException(message);
        }

        // be aware of grouping separators (like 1000 dots, etc.)
        int nrOfCommasAndDots = value.replaceAll("[^.,]", "").length();
        if (nrOfCommasAndDots > 1) {
            FacesMessage message = new FacesMessage();
            message.setSummary("Please use . as comma and do not use grouping");
            message.setDetail("Only one comma allowed");
            message.setSeverity(FacesMessage.SEVERITY_ERROR);
            throw new ConverterException(message);
        }

        // try to convert the given input
        try {
            // to be able to convert numbers separated by , -> convert , to .
            value = value.replace(',', '.');

            return Double.valueOf(Double.parseDouble(value));
        } catch (NumberFormatException e) { // not a number
            FacesMessage message = new FacesMessage();
            message.setSummary("Please enter a numeric value");
            message.setDetail("Provided value is not a double");
            message.setSeverity(FacesMessage.SEVERITY_ERROR);
            throw new ConverterException(message);
        }
    }

    /**
     * Method responsible for converting a double value to the representative
     * display string.
     * 
     * @param context
     *            FacesContext for the request being processed
     * @param component
     *            UIComponent with which this model object value is associated
     * @param value
     *            Integer or Double representation of the entered value.
     * 
     * @return String representation of the value for user display.
     */
    @Override
    public String getAsString(FacesContext context, UIComponent component, Object value) {
        if (value == null) {
            return "";
        }
        return Double.toString((Double) value);
    }
}