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    • dk.eobjects.metamodel.util.BooleanComparator Maven / Gradle / Ivy

    /**
 *  This file is part of MetaModel.
 *
 *  MetaModel is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  MetaModel 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with MetaModel.  If not, see .
 */
package dk.eobjects.metamodel.util;

import java.util.Comparator;

import org.apache.commons.math.MathException;
import org.apache.commons.math.util.DefaultTransformer;

public class BooleanComparator implements Comparator {

	private static BooleanComparator _instance = new BooleanComparator();

	private BooleanComparator() {
	}

	public static Comparator getComparator() {
		return _instance;
	}

	public static Comparable getComparable(Object object) {
		final Boolean b = toBoolean(object);
		return new Comparable() {

			public int compareTo(Object o) {
				return _instance.compare(b, o);
			}

			@Override
			public String toString() {
				return "BooleanComparable[boolean=" + b + "]";
			}
		};
	}

	public int compare(Object o1, Object o2) {
		Boolean b1 = toBoolean(o1);
		Boolean b2 = toBoolean(o2);
		return b1.compareTo(b2);
	}

	private static Boolean toBoolean(Object o) {
		if (o != null) {
			if (o instanceof Boolean) {
				return (Boolean) o;
			}
			if (o instanceof String) {
				try {
					return parseBoolean((String) o);
				} catch (IllegalArgumentException e) {
					return false;
				}
			}
			if (o instanceof Number) {
				try {
					double number = new DefaultTransformer().transform(o);
					if (number >= 1.0) {
						return true;
					}
				} catch (MathException e) {
				}
			}
		}
		return false;
	}

	/**
	 * Parses a string and returns a boolean representation of it. To parse the
	 * string the following values will be accepted, irrespective of case.
	 * 
      
	 * 
    • true
      • 
	 * 
    • false
      • 
	 * 
    • 1
      • 
	 * 
    • 0
      • 
	 * 
    • yes
      • 
	 * 
    • no
      • 
	 * 
    • y
      • 
	 * 
    • n
      • 
	 * 
    
	 * 
	 * @param string
	 *            the string to parse
	 * @return a boolean
	 * @throws IllegalArgumentException
	 *             if the string provided cannot be parsed as a boolean
	 */
	public static boolean parseBoolean(String string)
			throws IllegalArgumentException {
		string = string.trim();
		if ("true".equalsIgnoreCase(string) || "1".equals(string)
				|| "y".equalsIgnoreCase(string)
				|| "yes".equalsIgnoreCase(string)) {
			return true;
		} else if ("false".equalsIgnoreCase(string) || "0".equals(string)
				|| "n".equalsIgnoreCase(string)
				|| "no".equalsIgnoreCase(string)) {
			return false;
		} else {
			throw new IllegalArgumentException(
					"Could not get boolean value of string: " + string);
		}
	}

}
    
    
    
    

    




    
    
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