/*
 This file is part of the software framework JStatCom, 
 a library for building applications for data based analysis.

 Copyright (C) 2000-2005  Markus Kraetzig

 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
 */

package com.jstatcom.component;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.Locale;

/**
 * The NumberFormatTypes class contains formatters that are used by JStatCom components
 * to guarantee a consistent formatting behaviour. This class can be extended to provide
 * special number formatters in certain contexts. It contains an enumeration of
 * common formatters.
 * 

 * The defined operators override getInstance to initialize an instance
 * of the respective number format with a certain behaviour.
 * 
 * The class implements the typesave enum pattern (Joshua Bloch, "Effective Java", Item 21).
 * If you compare NumberFormatTypes, always use the == operator. This is
 * save, because they are Singletons (Gamma et al., 1995).
 * 

 * @author Markus Kraetzig
 */
public abstract class NumberFormatTypes {

    /**
     * The name of the NumberFormatTypes.
     */
    private final String name;
    /**
     * The default NumberFormatType to be used for representing doubles.
     * It displays numbers with Locale.ENGLISH, no grouping and a given precision, 
     * for example 2.345, 1.000. 
     */
    public static final NumberFormatTypes DEFAULT =
        new NumberFormatTypes("DEFAULT") {
        public NumberFormat getInstance() {
            NumberFormat format = NumberFormat.getInstance(Locale.ENGLISH);
            format.setMaximumFractionDigits(0);
            format.setMinimumFractionDigits(0);
            format.setGroupingUsed(false);
            return format;
        }
    };
    /**
     * The scientific notation NumberFormatType. The applied pattern is
     * "0.###E0. It displays numbers with Locale.ENGLISH, 
     * no grouping and a given precision, for example 1.234E-2, 1.000E3.
     */
    public static final NumberFormatTypes SCIENTIFIC =
        new NumberFormatTypes("SCIENTIFIC") {
        public NumberFormat getInstance() {
            NumberFormat format = NumberFormat.getInstance(Locale.ENGLISH);
            ((DecimalFormat) format).applyPattern("0.###E0");
            format.setGroupingUsed(false);
            return format;
        }

    };

/**
 * NumberFormatTypes constructor with a descriptive name. 
 */

protected NumberFormatTypes(String name) {
	super();
    this.name = name;
}


/**
 * Override prevention method to enforce 
 * a.equals(b) if and only if a==b.
 *
 * @param  o object to compare with
 * @return true if equal, false otherwise
 */
public final boolean equals(Object o) {
    return super.equals(o);
}


/**
 * Returns an instance of the respective NumberFormat.
 *
 * @return a number formatter
 */
public abstract NumberFormat getInstance();


/**
 * Gets the name of this type.
 * 
 * @return a descriptive name
 */
public final String getName() {
	return name;
}


/**
 * Override prevention method invokes super method.
 *
 * @return hash code
 */
public final int hashCode() {
    return super.hashCode();
}


/**
 * Gets a string representing this type, do not use for comparisons.
 *
 * @return string representation
 */
public final String toString() {
    return name;
}
}